You seem to be confusing lack of screen time with lack of personally, and rather conveniently at that. As Paul6 pointed out, she had her moments. Besides, my view is that the two Uhuras are very different and so far you seem in agreement with that position.
It's convenient because it happens to be true.
The major difference between the two Uhuras is that the old one was a barely-developed extra and the current Uhura is a full-fledged character with personality traits that go beyond "she's nice" and "she's professional".