The most obvious thing I can say is that tabletop design is a different entity from video game design. People who adapt books to screenplays don't use the exact same conventions and rules because you literally cannot get everything in there. That's not to say some of the rules mentioned here are good just for breaking out of the 5e design mold, but to say "things have to be this way because they are in 5e" isn't going to solve the issue. A 5e inspired video game is not going to take all the Rules As Written (tm) and turn combat into a slog to please some tabletop elitists. The problems as stated are problems for other reasons.
Cantrips creating surfaces are annoying because cantrips should not be strictly better to use than leveled spells, and yet oftentimes the fact that I can knock someone prone (and also spawn ice to potentially make them go prone again) with a cantrip is kind of annoying. I want to feel incentivized to use spells, not to not use them. And firebolt, lmao, I'm sure everyone's seen the threads on fire in this game. The terrain has always been annoying to me, and Larian loves their terrain, but even though they've toned it down a lot from Divinity 2 to BG3 I still think they need to reconsider what can create those surfaces.
But stuff like backstab giving advantage... I don't know if I mind? I know Jump is a little awkward right now because everyone's just bunnyhopping around the map, but I find the combat more fun than just running at an enemy and clicking on them. It's fun to have 2 bonus actions on a thief rogue. I love that fighters can throw people off cliffs and shit. The game is clearly balanced to make everything broken--casters get surface abuse, fighters get to backstab, rogues get to do whatever the hell they want. I think fighters probably got the worst of it which is where the complaints come from, but you toss in a totem barbarian that doesn't get affected by terrain effects or something and you've got yourself a crazy good time.
The problem with that is that Larian can easily keep the good parts of that while removing the godawful idiocy of breaking the action economy and letting everything jump through melee without penalty.
Put simply, nothing should have jump disengage that has it right now, except goblins and phase spiders. Everything else should have to worry about attacks of opportunity. Shoving should be an action. Surfaces should be nerfed into oblivion, and removed from cantrips (missing should not be doing more damage than a hit). These are simple, obvious fixes.
But in general, the game has implemented some very good points, including ranger tweaks (because PHB ranger is awful, and also unimplementable in a video game) Rogue thief tweaks (similar reasons-it's hard to keep track of what a thief can use fast hands with in a video game and they made most item interactions bonus actions anyway, although the current implementation should disallow two stabs), and other tweaks. But in general, the good tweaks are there to patch over implementation into a video game-not Larian's game engine. Larian's game engine is not perfect for this game, and Larian has not yet managed to work around that-and this is the main problem. There are many, many poor tweaks centered around this fact, and it's painful.