The reason why this strikes such a cord with me in TNG and not many other series is, well, the obvious. Gene Roddenberry, the creator of Star Trek, was in complete control. The same man who preaches that in Star Trek, humanity is perfect, greed and hunger are a thing of the past and that we can accomplish anything. He'll approve an episode where Picard says we've eliminated greed and the need for possessions while at the same time using a contract to take half of Alexander Courage's royalties from the work he did on composing the original series theme. Some example he was.
Well yeah, Roddenberry had his weaknesses was far from perfect, and the writing on TOS and TNG didn't always reflect his noble intentions. But I don't see how that invalidates the message of the show or anything.
These were still shows written by 20th century writers, after all, so it's only natural some of their antiquated ideas and attitudes were going to slip through. And they did still have to draw in male viewers, so of course there were going to be lots of pretty girls in sexy outfits.
It's still a TV show, after all.