aside from not being able to pose worth a damn due to the sculpts (somewhat hyperbole but I get it), I can't relate to the rest of those issues. The paint was much better and smoother back then (aside from series 6 halo 3, a generally problematic wave for the humanoid characters)
Halo Reach is where I can agree the paint quality actually took a disappointing dive. Halo 3 stuff was easy to paint, you got your undersuit and your glossy, matte or metallic armor plates on the top and they rarely fucked this up. Halo Reach, you had far more visual noise on the models, much more clutter, decals etc the type of paint jobs that would be hard to mass reproduce at such a small scale in toy form. This is why I only have like 6 Reach figures, all of which I had to repaint using the in-game models and shaders as reference. Hell, I'm not even completely satisfied with ThreeAs paint and weathering as far as game accuracy goes, but the monochrome Emile and Carter look pretty good.
Detail autism aside, I'd like some nice posable Halo "toys" as well, something you can fiddle around with. I can't really play with my mcfarlane collection because it's more of a stare but don't touch diorama with specific game-related themes for each shelf. They're just not very toyish figures, they are not fun to pose at all despite the meme articulation.
If I had to pick a company to do Halo figures right now, it would be Bandai (S.H figuarts or even model kits). They generally avoid stylization, their sculpts are usually great and their figures are super clean and very careful with any weathering, which I actually like. I don't think weathering should be mass produced, the results are rarely satisfying unless it's a monster or something. This is one thing I like about the 1000toys chief. It's clearly a toy and meant to be posed, it has that anime/comic book look to it. I just think the original CE chief is anime enough and didn't need further edits. I really don't like those new calves.