I think the faces are probably the hardest and most time-consuming things to get right, while everything else is easier.
But then I also believe that Playmates really had kids more than serious collectors in mind with this toyline (especially the smaller figures and toy props).
Playmates didn't have too much trouble getting decent face sculpts for Generations (for the non-regulars since they obviously would've had those down), and that movie went from shooting to release in about 7 months, whereas there was a 13 month span from shooting to the original release date of Trek XI.
I don't think it was the same situation. I think Playmates still had less time to do these larger number of figures well than they did the much smaller number of original figures they did with
Generations. It might also have been because Playmates rushed to sculp multiple waves simultaneously for Star Trek XI (one of the initial "sneak-peek" reports described what are likely Cadet Kirk and Admiral Pike, which did not appear in Wave 1). Possibly too many figures to crank out in too short a period of time (wasn't there supposed to be nearly 20 figures at the 3.75-inch scale alone?). I could see how the face sculps would suffer if they had to do them all in a few months, IMO.
This is all just going back to my original comment that they did a better job in the 90's on the Trek line.
Probably because they used different sculptors and manufacturing processes back then. Given how much time had passed since they last had the license, that's kinda to be expected. Even Hasbro's G.I. Joe and Star Wars figures have changed over the years.