Personally I don't like real time strategy for example. So I never play Age of Empires. But I don't go on their forums to complain their next game should be turn based.
This is a false equivalency. The issue is that something was a certain way and now it isn't and people want it the way it was before. The issue is not things are a certain way and people are saying it should be different, which is what your AOE example would be. That's what the people who welcome turn-based combat would do, not the people against it.
The current issue with BG3, would be like when XCOM got a new game back in 2012, but it used real-time combat instead of turn-based. People would be rightfully upset, as they are with BG3 scrapping rtwp combat.
Which is understandable to a degree. It's the same way people felt about Fallout Tactics or Fallout 3.
My argument would be that the core of the IP can still be captured regardless of gameplay (so long as it's still an RPG with the true lore), but I can certainly understand gameplay preferences or hopes for the game to play similar to past iterations.
I think ultimately the decision for TB was rather simple: Turn-based is far more accessible to a much larger population of gamers (see Pokémon), it's something the company is experienced with, it's far easier to balance for and it makes more sense with some of the mechanics they're trying out.
For transparency sake, I'm happy with the decision because I have a very difficult time enjoying RTwP. It's one of several things stopping me from truly enjoying PoE. I can play it, sure, and I enjoy the rest of the game, but combat is always a turn-off that way. I do hope that those who prefer RTwP are able to enjoy the game for what it is and (if it's a true BG game) even find it to be a great entry like New Vegas was to Fallout despite using Bethesda's assets/engine.
