The 2000s were the high point for aesthetic bickering. The Gen Xers who grew up with the original show were very loud in their rejection of Beast Wars and then the UT, and finally the Bay films. It even manifested in Classics like you said, where if people pushed back against the reinventions on hand someone was bound to reply in a snarky manner.
Younger fans, or even Gen Xers who weren't as tied to one vision for the franchise, pushed back.
Memes in the fandom like "Trukk not Monkey," "Pokeformers," "ruined my childhood," "Ruined FOREVER," and even "Geewun" are the product of that.
It's why I couldn't even post a picture of ER Barricade and SS '86 Frenzy as a wink to '07 without someone chiming in to go "you know back in the day SOME PEOPLE wanted to shove everything that wasn't G1 into G1."
Yeah and that was dumb. And the reaction to that was dumb. It was all dumb.
Now I'm not gonna bash anyone for standing up for new takes. The franchise lives and breaths on new takes and the people who wanted everything to be G1 forever were very, very wrong.
but when people start going "oh man those G1y designs in the Bumblebee movie are pretty cool but I hate that
the wrong people are gonna like them" or "wow Siege was a pretty good toyline engineering wise and I would have enjoyed it but they made most of the characters G1 guys so I can't" then mayhaps the aesthetic bickering has gone too far
I think the fandom in general is in a much better place today, with SS committed to a healthy mix of live action and '86 designs, and Generations pulling from all past iterations of the franchise, not just G1. Everyone has something out or on the horizon that they can get excited for, and the vibe's been much more pleasant.
But man. The fights between the "GEEWUN FOREVER" crowd and those who pushed back did a number on fandom discourse for a long while.