I've just completed Pathfinder Kingmaker (for unfamiliar Pathfinder is modified version of D&D 3.5 edition ruleset and Kingmaker is PC game) and I have few suggestions related to UI, players comfort and saving of our time in general (those systems are basically the same just tweaked here and there). Most of the things I'll describe below weren't included in most of the titles focusing around D&D theme like NWN series, BG, ICD etc. and now Kingmaker. Fortunately there were mods that improved qualitiy of gameplay (which were created qutie some time after game release) and it would be nice if those features would be included in BG3 since day one. Have in mind that all I describe below is my personal opinion. Feel free to add your own ideas.

1. Buffing. It would be nice to have a feature which shows that developers respect our time by giving us an option to buff our party with one click only. Or two for that matter. It simply take too much time to buff party before each fight, especially on higher levels when you have more spells and skills to use. Make an option to choose in advance spells we want to cast on our characters, those spells would be obviously spent and we would have to rest before using them again. Also this feature would work only outside of combat and we would still be given an option to cast those spells "normally" if we wanted to. In Kingmaker mod that provide possibility to buff our party with one click is called BuffBot and unfortunatelly it only gives us one configuration of spells which for me wasn't enough because I didn't want to use my best spells for trash fight etc.

2. Healing. Similar to buffing there is a mod that is using script made by developers which run with enabled option to spent our healing spells while we are resting. Someone took that script and modifed it for players (so we can heal with one click after encounter). The only objection I have for this mod is that it also used spontaneous casting for good aligned clerics and wasted every spell they had memorized untill everyone in party wasn't at full health (this should be optional).

3. Area of effects. I don't know how LS are going to solve this in their game but in PK some spells lasted after combat far too long! Like I had to wait for five minutes till barrier of blades disperse after combat. Either make those effects end right after combat or give us an option to remove them manually. Mod I was using provided two options. It simulated flow of time till those effects naturaly ended or we could dismiss them with one click (only outside of combat).

4. Hotbars. A lot of hotbars. I mean a lot! I was lacking those in many games... If I have a lot of skills and feats and magic items I need to have them on my hotbar! Some subclasses have a lot of those and combining them with 9 levels of magic spells? Yea go figure lad!

5. Respecialization. Some already mentioned it on this forum. Owlcats folded after playerbase whining and made it optional after patch. However. I didn't like how it worked there. The in game respec permitted to completely change your race, gender, class, character, day of birth, name, everything. It was second character creation. I think that respec should allow only to reset our character to level 1 (if you choose to be a fighter you should keep at least this first level without going full wizard mid game a.k.a. some sort of punishment should be imposed on you for breaking immersion). I have used respec few times in PK but only to change weapon focus smile

6. Difficulty. This was made perfect in Pathfinder! Well almost. From standard story mode to unfair with a lot of tweaks for those who like use custom settings. My objection? I started on normal and later have to set everything to max because it was too easy for me. I managed to build team that went through enemies like red-hot knife through butter:) Well maybe I'm exaggerating a bit but truth to be told it was possible for me to one shoot final boss (not the true true final boss:) on hardest difficulty. And the only real challange was boss from dlc.

7. Scrolls. Probably it is obvious for Larian devs and those who played BG but in PK learnable scrolls for wizards and other magic users weren't in any way highlighted (so you would know which you can learn as a wizard) till someone made mod that highlighted them in your and traders inventory...

8. Inventory. And items management in general. Imagine you are mid-end game and sold all of your items to one vendor only. Now imagine you want to buy back one item, of name which you do not remember, which you sold few levels ago. It is fun scrolling through hundreds of weapons or armors for five minutes right? NO! I'm not saying there wasn't an option to separate weapons from armors in PK, it was made quite well. However if you have 200 itmes in weapons subcategory this can be problematic. Just add an option to show katanas only or long swords only or sth. I'm not complaining about abundance of weapons in PK! NO! It is a big plus for Owlact devs for including so many of them in PK, much much more then in NWN1 for that matter.

9. Turn based combat. There were quite many disputes about it on this forum. Let me say this, I can esily assume that BG3 will be at least 200+ hours of game time (completionist). Now imagine you need to spend 5 minutes or more for each encounter. Not for me and surely not for BG3 the continuator of previous installemnts that worked in real time. But if you really feel like you need to make TBC make it optional. I'm sure it is possible and not that hard. Why? Because someone managed to made mod for PK and if one person can do this, whole game studio can do it to.

That is everything I can think off right now. I will add more stuff if something clever come to my mind. Also I would like to say that it wasn't my intention to spoil Pathfinder Kingmaker for those of you who felt that way. Quite the opposite truth to be told, it is a great game and fun to play (after year of patches XD) and can make time you are waiting for BG3 far more enjoyable. And I'm sure that BG3 will be a great game, after all Larians are far more experienced and trustworthy studio then quite new russian developer and they know how to make good RPGs.