The way I see it, the late 3rd Era Altmer were some of the most materialistic and spiritually effete people in Tamriel along with Imperials, only the former had more class and less drive. With all the effort they've put into art and technology and how decadent the Dunmer describe them to be, I can't imagine them really thinking they would be better off without Mundus, even if they pay lip service to an angsty religion which says they would be. And just before the Oblivion crisis when everyone thought the Empire was on it's last legs, they had their young calling for change and joining daedra cults.

Then the Thalmor came and attempted to use practical means of unmaking Mundus. I doubt most people know about that and I think it's quite possible that the Thalmor leadership could be the sort of environment that creates a Jagar Tharn figure who takes over it and aimlessly subverts the whole organisation from its orginal cause only the top knew about, even as the Thalmor as a whole grows more powerful. But I bet there are a lot of people outside the organisation looking back to better times without the Thalmor, when they could get up to whatever recreational pursuits they wanted.

Do you think that these people could form a resistance movement rather than those who want to save and liberate the barbarians on the mainland? Perhaps the Thalmor's and the rebels' aims could be unmake the world vs. some Brave New World scenario where life is static, luxurious, fun and purposeless.

And how would TES:O High Elves' aspirations compare? Perhaps it would be more appropriate for a time when Elves were running Tamriel.
Although maybe Thalmor life is just fine for Altmer who don't argue.