I see two sets of complaints here, and I think both are fair. The first is aesthetic - that the perpetual downward angles makes the whole thing feel a bit claustrophobic. It's a very unusual look and feel for a 3D environment, and not in a good way.
The second is functional. When you're fighting with the camera angles to actually perform actions that the game *should* allow you to do, that's a real UI problem. Because the game actually *does* take place in three dimensions, but the display is reminiscent of a 2D display, that creates functional restrictions that are tantamount to bugs, or that at least disrupt continuity.
I've had problems where I couldn't get the camera to properly picture a redcap on a distant hilltop, where I couldn't get the game to show terrain I wanted (and should be able) to Misty Step to, or where I simply couldn't get an angle to be able to select an elevated target. Never mind the planning problems of figuring out line-of-sight to an enemy on an upper level when you can't see where the ceiling is.
One of the joys of the 3D game environment is that it allows for puzzles that require the character to be aware of all dimensions - don't forget to look up. And, to some extent, BG3 *uses* that.
Consider, for instance, the stone that can be dropped on the cracked tile in the overgrown ruins.
Took me a while to find that because, well,
I couldn't see it.
Asking for a full 'first person view' where you can look up...requires Larian to create a ceiling and sky textures which I suspect aren't there. It's a relatively big ask, going beyond a tweak to the UI, but for a game of this nature, not closing in the 3D environment is kind of a big cut corner anyways. However, giving a greater degree of control over the camera - for example, being able to manually move it along the vertical axis - should be relatively simple, solving some of these issues.