The quality drop past act1 was very noticable, but it is easy to fall into "ah, they will fixed it later, like they fixed early access area". So when it doesn't happen, should one pretend that all is hunky dory?
One doesn't need to pretend. It just IS hunky dory.
Larian didn't say they'll fix it later, they didn't say they'll eventually make Acts 2 and 3 the same quality as Act 1, even with prior Larian titles they never made any later Acts equal to their respective Act 1's.
You made the assumption that they'd fix it. But there's a reason for the saying "When you assume, you make an ass out of u and me". That's because banking on an assumption will often lead to disappointment.
There was never any real reason to expect later Acts to be given the same level of development and attention to detail as Act 1 and as such, it's perfectly okay in the grand scheme of things that it remains the case.