That said, I don't think it should be illegal. Criminalizing has more bad than good effects. Prostitution is called "the oldest business of all" for a reason: No criminalization effort will always be successful ending it. So we should better try to minimize the damage -- providing a legal frame and controls, for that there is no involuntary prostitution, pimping or human trafficking. The ugly side effects sourrounding illegal prostitution should be dried out. There should be health controls and prostitutes should enjoy the benefits like other employees too.
As long as there is demand, there will be supply, so we better do our best to regulate and control this business instead of leaving it to criminals, including all aforementioned horrible side effects.
I don't see a contradiction to this approach on one side, and campaigns to morally prescribe prostitution. We can do both, legalize the business, but decreasing demand at the same time.