You are viewing a 1960's tv show through politically correct glasses. Short miniskirts were in vogue at the time. One might as well complain about the NASA astronaut who keeps a female genie dressed as a harem girl all the time. ;)

Kirk was pretending to be his evil counterpart in a hostile alternate universe, and you darn well know it!

The cast was getting older in the 80's, and the plots really didn't throw a sexy alien captain Kirk's way. His relationship with Gillian in The Voyage Home didn't voyage out of the friend zone. Kirk got friendly with David Bowie's wife in The Undiscovered Country though.

Kirk's sex drive has resurfaced in the new movies. You never had a female character strip down to their undies on the tv series though.