I'm not sure "Nemesis" and "legacy" sound like a good match to me, considering 90% of anybody's Nemesis's games end with the death of their characters. :)

I'm really interested in your thoughts about legacy games, but I wish the next time that you talk about them you'd focus on the aspect that creates the real controversy: resettable vs. non-resettable. To sum it up:
1) As you said, legacy games are a way to start small and then add a bunch of expansion-like mechanics over a course of several playthroughs. That's great.
2) So I bought my 100+ bucks game, played with my group for 3 months, 6 months, whatever. Had a great time. Now what?
3) As you said, very few hobby players would reset and replay a full campaign of that kind of game. They'll just play something else instead. So now what?
4) If the game is non-resettable, I can't sell it or pass it to friends. I only have two choices: either I keep it on my shelf to collect dust for the rest of my life, or I throw it in the garbage.
5) And giving those only two choices is hateful and inconsiderate (to you as a customer and to the environment too) on the publisher's part. Especially because it's FAR from necessary. You don't need to rip cards! That's just a stupid gimmick. You don't need silly stickers. Many many games engineer full campaigns without asking you do irrevocable damage to your game. It's a thrill for some, but it's akin to burning money for fun. I played 10 sessions of the campaign of It's a Wonderful World, and I can just sell it now. Even better, all those mechanics and components turn into expansions at the end of the campaign, so I can either reset and sell the campaign or consider I bought two things for the price of one: a campaign and an expansion for the base game. It's not really rocket science, it's not asking too much.
I feel like designers and publishers that still take the "rip cards apart, throw game in the garbage" route (luckily, they're increasingly rare) are just doing it to challenge players and maybe to make them lose their product so they'll buy a separate box with similar mechanics rebranded as expansion.