This su.mer, i attended a performance of TOSCA and my absolute favorite kind of audience was in the theatre...that is, 2/3 of them were at their first opera performance! They clapped at all the right times, they even applauded when Tosca made her first entrance on stage. They also clapped at the wrong times...like when Tosca stabbed Scarpia and the firing squad received an ovation when they shot Cavaradossi. They booed Scarpia, and he took it in stride. I loved it because the opera CONNECTED with the audience. A new audience for opera was born that night. It was refreshing, it was FUN! BTW, It was a traditional performance, not one UFO, the floor wasn't a mirror, no hospital gurnies, no steel beams, no stainless steel refrigerator doors in sight! So here, a new audience fell in love with opera set in its proper setting-noisily and completely.

#1 language: in 1966, Boris Godowsky was a guest at Brevard Music Camp. He was asked about our singing operas there in English. His response: Just as there are master librettists and composers, there are master translators. Just as there are bad librettists and composers, there are bad translators. When a master translator transcribes the Italian, German, or other language into another, both music and spoken language are given equal consideration, and there can be as much art in a good translation as there can be in the music.

Part of what I love about opera is hearing the different languages.

I took my husband, who speaks French, to see Carmen and asked him if he could understand anything and he said “Yes, the parts where they were talking.”

Subtitles work fine for me, and, for what it’s worth, opera has improved my understanding of French and Italian.

there's like 1500 seats at my local opera theatre
if everyone was talking and going in and out i wouldn't be able to hear anything

I was recently in a production of La Boheme (as part of the chorus) that was set in the modern day. Everyone was dressed in jeans, hoodies, etc. (and the set honestly looked more like the musical inspired by the opera than the opera itself!) And we only found out about this on the first staging rehearsal. At no point during the auditions or music rehearsals did ANYONE communicate to us that this would be a modernized production.
Personally, I was pissed. The only reason I auditioned for the opera (because, let’s be honest, there’s really not that much for the chorus in Boheme) was because I love vintage clothing and was excited to wear the Victorian-style costumes. Jeans and a T-shirt? Boring! I can wear that anytime! But by that point it was too late to quit, especially since we had a very small chorus so they really couldn’t afford to lose anyone.
Worse, nowhere in the advertising did they mention that this was a modernized production; they actually used photos from the company’s last production of La Boheme (which was a traditional production) to promote it, which felt totally misleading to me.
I agree that if companies are going to radically change an opera, they need to be upfront about it — not only to the audience, but to the performers as well, so we don’t feel like we’ve been baited-and-switched.

I once went to an opera where someone announced at the beginning that the audience was encouraged to make whatever noise felt natural to them, so there was a lot of laughing, gasping, applauding in the middle of a movement, etc. It was fun and made sense!

OMG the comment about french pronunciation. I'm a percussionist, and while I lived in Long Beach studying my master's I got free tickets for the LA Opera doing Carmen. They opted for the version with dialogue and all of the cast was either spanish or italian singers. Naturally when I came back my private teacher was asking me what i thought of the percussion playing (did you like the tambourine sound? what about the triangle excerpt?) All I could think to say was "I don't care about that, they butchered French dialogue and they are a professional company, that's what I was listening to!" My teacher was surprised that I wasn't zero-ing in on my instrument. I think that also speaks highly of the American conservatoire tradition of teaching students to only evaluate the merits of an orchestral concert by the performances of their specific instrument rather than as a whole picture.

It's my understanding that the "original language movement" was a product of modern travel. Previously countries mostly did performances in the local language but when stars began travelling a lot (as in singing in 10 or more countries in a single year) the idea was that everybody use the same version of the opera and the original was the optimal choice.

By the way, Viena state opera recently staged Cavalleria Rústicana, right place, right time, stage and set as Mascagni likely stipulated, it was refreshing to see!

Eccentric settings are a thing with drama as well. The Onion even had an article years ago about a maverick new director who sets Shakespeare plays in their actual historical settings instead of outer space or 1920s Chicago.

I don't enjoy  performance when people are distracting around me. If i paid money to see a live performance, then i should be able to hear the performance, not the people in the audience whom i didn't pay to hear. So although we should always be tolerant of some level of caughing, sneezing, etc., but someone singing along with the famous tenor i paid money to hear????  Uh... NO. That's simply not fair. Then what's the point of a live performance if it's nothing but an annoyance. This is just respect for other people's experiencing of the performance

I once saw a Baroque French opera with a Greek theme, that was reset as vegetables in a fridge. The stage had an amazing giant fridge as a set. The door opened and a human sized brocoli began to sing. It was expensive and very risky, and got panned mostly by the UK media!! I think there are clips on YouTube somewhere

#2 setting: After you mentioned that you might as well change the music if you're going to change the setting, you mentioned Romeo and Juliet. There's the perfect example of why you're right that you need to change one if you change the other: West Side Story! It wasn't enough to just change the setting; Bernstein was savvy enough to also change the music, and did so wonderfully.

Church did not always mean the "bourgeous public space". In some churches you can still mill about, kiss icons, walk, dance, say "amen". The tradition of clapping at Mozarts time was more interactive like in jazz, as Mozart himself reported from performing i Paris as a youngster.

After ushering in many live classical performance venues, Glasses of wine are frequently spilled and often on the chair and the people in the adjacent seats.

About singing in the original languages, I have TWO opinions:  each language has its own 'music':  rhythms, pitches, colors, which the composer heard when he was writing the actual music.  When you change the language, aside from the obvious rhythmic differences there usually are, there is a more subtle something that is a little off. I have most often noticed this when singing in French; my vowels are different, my mouth is less open than when I sing in Italian, whether right or wrong.  I learned the Verdi aria "Merci, jeunes amies" in French first, and then in Italian ("Merce dilette amiche") from I Vespri Siciliani (because Sills sang it in French and Sutherland in Italian, and those are my GIRLS).  You may know that it was originally written in French and shortly after translated into Italian with Verdi's blessing.  The French just sounds and feels better to me. This same thing is true especially for things I've sung in English from the original because the vowels are problematic. For instance, I've sung the Queen of the Night more than any other role, and often in English, but when I sing the arias in German, the recits work better--it's like the German makes my voice stronger, more commanding, and maybe that's because the recits are down in the speaking range.  But even the text in arias works better for her character in German....spitting out those multiple consonants!   Of course, there is also the argument that for sopranos, once you get above a certain range, the vowels all modify themselves into 'ah' basically, so it doesn't matter what language you're singing in (and as you know, composers give coloraturas "ah" to sing up there for that reason). (I read a really interesting article in Scientific American about this phenomenon.)  All that being said, I want my audience to know what I'm saying, and I know Americans are not multi-lingual as so many Europeans are.  Supertitles make sense to me.

Speaking of food and drinks, my local opera company is contracted with an auditorium (1900 seats) and they sell reusable cups with lids so you can drink in the theater. All the local theaters have adopted this practice too. We’re even allowed to wear jeans if we attend shows. The company is just happy for people to attend.

Honestly, the language thing…. I’ve seen several operas sung in my mother tongue - did not understand a single word. So no, this point does not make sense to me.
The setting point I partly agree with, but I have seen examples that totally made a new setting work. This also happens to other art forms, especially plays (Shakespeare is a great example) and an opera is basically a play. Since you mentioned Romeo & Juliet - how did the Buz Lurman movie not work? And that setting was completely weird.
I absolutely feel your fifth point and you worded it beautifully hilarious.