Just presenting edge cases is not a great argument for a game, where you should be able to play with any given party and the balancing is worked out for that. You already see how they had to come up with new ways to circumvent the rebalancing issues they created, namely the abundance of healing potions and food that heals you. Which in is just another factor, that invalidates balance between the classes, as martial classes get another edge over spellcasters. Martials are restrained by their HP normally. But with healing this abundant you dont really need to rest, so they can go all day long with just basic attacks, while spellcasters would be severely hindered in doing anything meaningful.
Except its not an edge case. I have finished the entire EA with a single character, not taking advantage of surfaces at all. I have also finished it with a party and the party only had to rest 3 times throughout the entire playthrough. And no, it wasn't because I ate stuff after every fight, its because for most fights you can either alpha strike enemies during a surprise round, giving them no chance at all to respond, or because there are plenty of environmental obstacles you can take advantage of to constrain enemies. The game does not force you to use surfaces at all, you can use them if you wish to. You are also not forced to rest after every encounter. If you can finish the EA with a single character, pretty much any party of 4 will also manage.
The first two are really shallow and not really a tactical play. Because as long as the surface is not killing you outright, there is no downside. Healing is abundant and just a BA, so what gives? No trade-off really. Even if 1-2 of your PCs die, just rezz them.
The latter two are just a cascade that becomes necessary because of the implementation of surfaces in the first place. And if they get implemented there will be other stuff to rebalance again.
They make it harder with every step to deliver a balanced experience, as they stumble from one "Fix" to another, all the while a mostly balanced option is ignored. As I said, I love DOS. More fun than I had in a long time. But Larian should not be afraid to (mostly) trust the 5e rules as they are. The people at WOTC had some great ideas there, and they paid off immensely. Make the systems work on PC and in the engine and trust the success that is 5e.
Healing costs you a bonus action, which is very definitely not "just a bonus action." If you are a warlock or a ranger, consuming a heal is costing you 1d6 damage from reapplying hex or reapplying hunter's mark. If you are dual wielding, its costing you an additional hit. The overabundance of healing items does not negate the fact that there is a meaningful consideration to make. The correct solution there is very clearly to reduce the number of healing items, so there is a genuine risk of running out of them.
See the thing that you don't get is this: 5e does not revolve around the management of surfaces and items that create surfaces. It is based around the action economy. While 5e does have some items that would create "surfaces" you will be hard pressed to find them the core of the combat or being widely used because in 5e they are simply less efficient and the system does not emphasise their effects. A good example is the spell "Grease", that spell is a CC spell, its not a "primer" to set it on fire.
That is the issue. BG3 is centered around surface interaction, its not an optional part, it is the very core of the combat system and thats just not what 5e is about.
The moment I found "grenades" in the intro scene I knew where this was going, I played DOS2.
The thing you don't get is, my care for what system of rules they use is absolutely 0. I am mostly interested in playing a game with tactical combat. If a change to the ruleset adds some tactical considerations and makes the combat more interesting from my PoV, I am all for it. I care very little about the story, because if I judge RPGs on their story, I then compare them to books and the writing in games is nowhere near comparable to something like Dostoevsky. The early access is about us as players giving our feedback on what we like/dislike about the game. Obviously, that means that there will be a lot of disagreement, because there will be both players like me, who don't care 1 whit about "the ruleset" as well as players like you, who do.