The problem is that you're comparing Star Trek (1966 - 1969) to television from this century.
Seriously, compare the role of Uhura to anything else that was on the air or in the theatres at that time.
She wasn't the mom or the maid. She wasn't blonde. She was a female character in a position of responsibility, even if her job was just to repeat everything the computer says, and did things which were more important than baking cookies for the male characters or screaming whenever the villain showed up.
You didn't see much of that on "The Lucy Show", "The Jackie Gleason Show", "The Beverley Hillbillies", "Hogan's Heroes", "Hawaii Five-O", "Casino Royale", "Thoroughly Modern Millie", or "Lost in Space".
But don't listen to me, listen to what Dr. Martin Luther King had to say about it.