it's not that nudity is a bad thing, it's that slinging tits around to keep around some perverted losers is just a sleazy business tactic.
fanservice isn't aimed at the normal person watching a show, it's aimed at keeping the people they know are watching, perverted nerds that probably don't get any irl. it's kind of an insult actually, like that's the only type of person that'll watch anime or something.