You don't need to lower AC, you already have at level 1 all at your disposal to deal with it. Use the Sleep spell to immobilize 4 or even more (if they wouldn't have too much HP). Sacrad Flame spell of cleric targets dex saves which means an almost safe hit against sleeping enemies. Just as example.
Again, you just don't understand the context of the whole thing here.
- It's not a TT game between D&D geeks, this is a game for millions of players world wide with hundreds of thousands of them not doing even 1 TT game ever or even D&D game ever. People are not born with inherent knowledge of all D&D 5e intricacies - all they will see is 40% hit chance and after couple of battles where they will drool on keyboard they are gone with Metacritic and what not going down.
- What we test now is a
normal difficulty, not tactician. It's a difficulty players are expected to tackle when they fire up the game.
- This being a video game - it allows much more complex and bigger encounters unmanageable in TT sessions, difficulty and challenge can come here in other ways than just high AC and winging it with dice and RNG - a cheapest thing to boost difficulty in games.
- Burned actions in turn-based video games are frowned upon as a whole. While people understand you can't succeed all the time, they do expect a reasonable return for investment overall. That's why we can do more in action as is, btw. Last thing Larian needs is just to frustrate people by making them fight excessive RNG all the time. There will be enough of that as is.
- Surfaces in BG3 are more available than in TT and more exploitable too. Creatures need a bit higher HP to compensate that too.
This is the context. Realize - this is a video game, not TT run.