Did they limit Uhura's scenes because of Nichelle Nichols weight?
If they did, I'm not saying I would agree with that decision personally.
But like several other posters, I noticed that Uhura didn't get much screen time in this one. And when she was onscreen, she was usually sitting behind a very large control panel.
Then came The Voyage Home - where the producers made the decision to stop trying to hide the actors' advancing ages - and we all immediately noticed that Scotty and Uhura had put on more than just a bit of weight.
Were they trying to hide the fact that Nichelle didn't quite have the same voluptuous figure she sported so well during her mini-skirt days in TOS?