I definitely felt my heart sink when they announced civ switching, but I put it down to my disillusionment at how badly Humankind handled the mechanic and gave it another chance. I do think they did it better than Humankind, but that's a low, low bar.
Introducing it differently might have won over a set of players, but I suspect there'd still be a large cohort of players who can't be won over to civ switching by any means. That being players who like to "main" a specific civ. This isn't necessarily for nationalistic reasons either, I know plenty of players who found the civ in 6 that just *fit* their playstyle and they didn't want to play anything else. So, I suspect there is some overlap with the group that would complain about political choices in Civ7, but that it is a separate bloc to a reasonable extent. In my regular MP group, those players they make up about 1/3 of the group, they unanimously will not switch to Civ7 as long as civ switching is in there, and I wouldn't be surprised if that proportion translates to the wider community...
I agree with comments about eras being something that will eventually become normalized in some form in 4X games. But, I think there are enough players who connect with only one civ, and even for those who don't there is an emotional gut punch that comes with civ switching, that I don't think devs can solve it as a mechanic. It feels like a loss, not a gain, in the majority of Civ7 games I've played, and I enjoy Civ7 - I should be the target audience that likes it.
For me, personally, eras and civ switching also have an awkward interaction in 7 where the civs that I am excited by are not evenly distributed. I like all but a couple of the antiquity civs, about a third of the exploration civs, and among the modern civs, Siam is probably my only "hit" - the other 2 that excited me thematically, don't excite me mechanically. As the game goes on I really lose my excitement to play. I imagine though that there are plenty who go the other way and feel like it's an uphill struggle to reach their civ of choice.