The fact that one of the people doing the analysis only did so for the first book is certainly interesting. Can we normalize not labeling a character for where they are at the beginning of their ark?

Because Xaden Riorson does show character development, and a significant deal of it. Yes, he starts off controlling, and while his trauma explains it, it never excuses it. Violet does call him out, and then he realizes it was wrong to do so, apologizes and actively works to change his behaviour and his attitude and be better. By Onyx Storm, not only he is he no longer controlling, he has become one of the most supportive and affectionate partners I've ever seen in a book. There is active and gradual progression and improvement.

And even the example you gave from the first book is slightly out of context. He never places a guard outside her door, he just puts in a magical protection in place so that people can't break into her room and try to kill her in her sleep...which had already happened. Not to mention there's an additional magic complication that if she dies, he also dies. So after she's almost killed, he takes precautions and the young man he does assign to act as her bodyguard during the day even says "I'm sorry, I know it's not fair."  Xaden's protectiveness is often also framed as annoying. But he still treats her with respect and trains her so she can eventually defend herself. Big difference from how Dain acts and even then, Violet later comes to recognize she overreacted and apologizes to Dain too. And Dain actually did violate her boundaries and privacy in a very significant way, which Xaden never does, that's important.

It's so ironic that despite all the past screeching about Male Authors being problematic, it is continually female authors who write about and romanticise "problematic" male characters. I never want to hear a woman make fun of "breasting boobily"s ever again after seeing what modern ""fantasy"" [thinly veiled smut-shlock] has to offer.

I have a lot of interconnecting theories about this, but one of them is that a lot of women are more interested in kink than they realize, and they don't realise this because no one (including men!) gets any actual sexual education around sex as pleasure and how to communicate about it.

The dominance dynamic that is so popular in a lot of romantasy is a shaky imitation of a D/s kink dynamic, but without any clear expression of the very necessary consent and communication practices. There is a wide swath of people out there with unmet sexual needs that they don't have the language or sense of safety to express; despite all the legitimate issues in these books that are very worthy of criticism, they HAVE provided a language to express some of those needs. It's a language with many flaws, but when the only one you've been given is shame and silence, it's no wonder romantasy feels like a revelation and the only safe way to have that need met.