As an example, if World of Warcraft was a completely different looking game, with different music, sound effects, quest text and a completely different art choice, but the gameplay layer were exactly the same, the people I met were the same, but I just couldn't get into it and couldn't get past the differences in this hypothetical WoW, you could characterize that as an entirely emotional decision, especially if you had the other experience to compare it to, however, you'd be conflating two very different experiences, even if both are "emotional".
I'm with you on some criticisms being just complaints without substance, but even though I also pointed out that civ switching can be entirely cosmetic, it is closely tied to gameplay choices. Would they have chosen to implement this version of eras without it? Maybe. They certainly could. But how different would it feel? It would be a very different reality, one which might lower the resistance of a lot of players to these mechcanics. Then maybe they could polish those mechanics and move towards civ switching in a more "integrated" way in the future, where you choose new civ bonuses, have a narrative about becoming a horse people like Mongols, or an early industrial power in the modern era, and maybe we'd be in an alternate universe where we arrived at the exact same gameplay and yet everyone who is complaining on these forums might instead be praising the game. We'll never know.
I hope they overcome the criticisms in the long-term and stay on this track gameplay wise, with improvements to transitions and polish in the later eras. But I can't dismiss all criticism of the civ switching as merely emotional when everything is so intertwined and they took so big a swing.