1) marking red field of vision when sneaking (same as DOS - proposing to change this visual),
2) using fog clouds animations (same as DOS, please remove this visual and make it a PC/NPC status),
3) overusing surfaces interactions (water, grease, blood etd - same as DOS; please enough with DOS features),
4) to much items and overly large inventories (same as DOS - BG1and2 had relatively small inventories, I would propose to somehow simplify the item gathering process or even use a mechanic like a courier similar to what they did in Torchlight - it can pick up generic items and sell them with on or two clicks)
5) making the combat not look so similar to DOS (changing/removing the attack path line visual)
6) changing the jumping animation to something a bit more realistic (i think nobody was really impressed when Swen Vicke showcased the feather spell and jumped of the building - that spell is a rip off from Morrowind etc.)
I must say, I find many complaints by OP absurd. Little in terms of arguing why would BG3 benefit of those changes beside not reminding OP that the team made D:OS2 as well.
1) Why? Is there anything wrong with it? It could look nicer and smoother, but cone of vision is a great stealth feature and it is implimented clearly and intuitively.
2) What's wrong with it, beside appearing in D:OS2? I do find an idea of "zone of darkness" to be rather silly, though in the world of magic anything is possible I suppose. Gameplay wise it seems like a neat design, with multitude of uses. Overall, intrigued by advenrtised stealth features.
3) I actually haven't seen much of it. I do agree that D:OS relied a bit too much on those, but those are good features, that can help making location and encounters unique and memorable. In tabletop you can use spells and abilities to interact with stuff around you. In Pillars those can be in scripted interactions. BG3 has a potential for a very robust enviroment interactions and as long as they won't overshadow the actual DnD system, they are neat.
4) I will hold my judgement on that. I was not a fan of inventory in D:OS2, or should I say - mostly trash item design. Now, BG2 inventory wasn't that small - it's just potions, gems, scrolls and plenty of weapons were carried in their own inventories, inside the inventory - a feature that can be easily replaced by a proper filtering options. Afterall, one was never forced to leave anything valuable behind in BG2.
5) UI has a chance to change - a lot of stuff is currently reused to accelerate development and things will be finalized later in development. Still, you fail to mention what's so wrong with it, beside being similar (or same) as their previous title.
6) Yeah, I would prefer if they found a way to make jump more believable. I get that they want it to be far, for gameplay purposes, but even with enhanced abilities it just looks silly right now. A lot could be improved with a bit more fluid animations though.