I was annoyed by this a lot when the ST reboot came out. "OMG WHY DIDN'T THEY LET UHURA FIGHT THEY'RE SEXIST!" - especially in relation to the bar fight. No, princess. Uhura did not abstain from kicking Kirk's ass because she was too much of a lady; she abstained from kicking Kirk's ass because she knew that getting into a bar fight just because some guy was hitting on her would be a foolish thing to do. If she had been in actual danger it would have been different.