It's true a lot of religious folk have tended to be more obsessed with sex than is entirely healthy. It's one of those things people can get stuck on either way. I've seen some anti-sex religious folks who clearly think about it far more than the average person does, which is all kinds of ironic. And a lot of the prohibitions that one sees, while they might have made sense in a certain cultural context, they don't necessarily apply today. People ought to be open-minded enough to allow for revisions like that. Or hew to the principle rather than the letter.
At the same time, licentiousness isn't really freedom either. People who just obey their impulses are no less slaves for it; they didn't choose their impulses, after all. True freedom comes from not being controlled by laws or impulses, but making informed and conscientious decisions, with a reasonable view of the consequences. And that does require some moral principles to start with, or else you're right back to making decisions based on unchosen impulses.
So basically, while having a negative attitude towards sexuality isn't healthy, that doesn't mean that having zero boundaries or inhibitions is healthy either. As with most things, the healthy road is the third option.