I didn't say that mechanics BG3 are perfect, I said it's OK if it differs from the mechanics BG2.
Just like you, I think that many things need to be changed. For example, I hate jumping and I also want party formations and other things. But these mechanics (like party formations) was not only in BG or BG2. I say "we need changes, these mechanics are inconvenient", but I don't say "we need what was in BG2!" because I don't think this is quite correct.
I just think lore, characters, and events more important when you compare one game in a series with another. Many games have similar mechanics this is not something unique. So when someone says "this game is not like the previous one!" I think they're talking about lore or atmosphere or other things like this, not about menu and font...
Games are interactive media; mechanics & interface determine the interactions between the player and the game's lore, setting and characters. In my opinion BG2's huge success (at that time) was due to the developers finding the right combination of an epic story, a D&D-based fantasy setting, a memorable companion cast and enjoyable gameplay and mechanics. Such as for example being able to play with a party of six, as opposed to four. Six is, after all, a number much closer to the original fellowship of the ring. And yet somehow many developers fail to consider that it was a fellowship, not just adventures of Frodo, even as they keep reusing Tolkien-inspired content in their games.
