Since you're the only person in your session, what isn't fun?
I see digital cRPG as constant interaction between the player and digital DM - so how campaign is structured, what it allows for, what it encourages and rewards is, I think, rather important part of the experience. As to make clear what my issues are when it comes to combat:
I never had a massive problem with barrelmancy - because, like you said, for the most part it is a mechanic I can just not abuse. My two current main issues with combat system are:
1) Push
2) surfaces
The problem I have is that I can't quite opt out of those. Like highground before, I find push in many combat encounters to be single most deciding factor in how combat will procede. The only way I can "ignore it" is by adjusting my tactics specifically to avoid it (like avoiding going anywhere near drops - and with how riddiculus push range is, I mean ANYWERE near. At least, it seems Larian redesigned combat encounter right before Grimforge - the pushfest that was happening there was a joke. Hilarious, but not... good.
Surfaces on the other hand, make it really difficult to engage with the systems that I am at least used to thinking of as core part of DnD - spells. With surfaces doing guaranteed damage, and things like throws having what seems like practically unlimited range keeping any buff/debuff for even one turn seems like an impossible task - those are systems for which concentration wasn't designed for.
So not only those are mechanics that I don't think are very interesting or rewarding to use, but they actively interfier with other combat mechanics overpowering them. Even if they weren't use against me, I still believe their current implimentation is bad to the overall gameplay - if game tasks you with problems to figure out, and the best answer is always option A, then I think it is just uninteresting, even if I can solve the problem in more complex way and satisfying way. At this point I, as a player, have to create a challenge for myself (and by challenge I don't mean difficulty - just odds to overcome) meaning that game itself doesn't provide much to offer. It's a bit "If you don't like game's story, you can write your own". Yes I can (or rather: I probably can't - I am not a writer/game designer. I know I like a good coffee, but in spite of how hard I try, I can't seem to replicate it at home. Still if I go to a specialty coffee place and pay £3+ for a cup I do expect them to do a half-decent job.)
After those two, would be stealth and stealing - and while I can not use those, and I don't, lack of balanced implementation that would play nice with other systems cut into replaybility of the game. Stealthy characters, luckily aren't my "go-to" but if I want to replay the game as thief, using those mechanics too greatly imbalance the experience. Perhaps, I am extra salty about this one, as the first character I created in BG3 was a thief - only to find that stealthy/stealy play isn't enjoyable.
After spending some time in online forums I realised that people look for quite different things in games. My tastes seems to allign quite closely with Josh Sawyer, so I will just add
link to his argument for a need of reasonable balance in a single player cRPG.
As to argument that asking for better balanced experience would ruin game for everyone else - did nerf to highground and backstab break the experience for anyone?
EDIT:
So trying to force enemy NPCs into a potential bottleneck, by breaking a ladder, is cheese now? Maybe, just maybe, someone puts a ranged character up on a bridge not because "Combat Advantage" per the rules, but "Combat Advantage" because it takes longer for the target to actually get to them, and maybe they'll be dead before they do? In every other game I've played, this is called thinking tactically, here, it's cheese?
Forgot about that. That would be ideal situation - for push, positioning, use of enviroment to be tactical considerations. Best examples I can give are changes Larian already did - prior to patch6 I did consider high ground to be "cheese". It pretty much made "chances to hit" irrelevant, was more powerful then defencive spells I could cast, was easy to obtain, and enemies were wired to abuse it (as they are with push) - to have high ground was simply the thing to do to win any encounter. Now it's a tactical consideration - it's benefits and can be comboed and countered with other systems.
The reason I am perceiving as breaking the ladder as "cheese" is because AI is not capable of responding to it properly. But, like with barrels, it is just something I can ignore, but it does take away from a fun of the "challenge" - I much prefer game where I can use all tools on my disposal and trust that the game won't freak out - at least not as easily as BG3 does. Perhaps that's the cost of ambition, and would enforce my preference was smaller focused titles. It's a bit like using AoE spells, like stinking clouds in BG1&2 to kill dragons without triggering combat. It breaks believability of the situation, and therefore found it a bit lame to discover. But again - not a big problem IMO compared to things I have mentioned - it just feels sloppy. If narrative goal of making this challenge harder then other content was to underlie how dangerous the Gith are, than that kind of stuff detracts from it. Just like DS1 bosses loose their mystique once you discover they don't know how to deal with hugs. What confuses me is that those kind of things are usually a result of devs oversights - not expecting players to play the way they do. Larian seems proud of those, and I just don't connect with that. To me it's like a musician being proud of playing out of tune.