They really did seem to try and present good stories, but with perhaps 22 minutes to work with, there wasn't a lot they could do for characterization.
Depends on the character. I daresay Uhura was given more to do in TAS than she was in TOS. Sulu also got to be pretty prominent.
. By necessity they had to have a greater focus on the narrative of the episodes because they had much less screen time to tell their stories than they did in TOS, but I do think there are some sections of fandom which tend to downplay just how well TAS serviced the main characters, particularly
the ones outside the 'big three'. It did a great deal more with the characters than some would have us believe.