Decriminalization isn't legalization. We should be looking at countries where it's entirely legal, prostitutes have guaranteed work conditions etc.
http://en.wikipedia.org/wiki/Prostitution_in_the_Netherlands...
Sure, there might be better ways of solving this than making prostitution illegal.
If you walk through the red light district of Amsterdam at any given time of day there will be tourists packed wall-to-wall and relatively few locals (they are mostly on the 'supply side').
If every country would legalize prostitution the draw of this would be greatly reduced and Amsterdam would lose some tourist income (I'd be more than happy with that).
Drugs same thing. I don't know any dutch people that consume on a regular basis but almost all the tourists that I know and meet going to Amsterdam can't wait to get stoned.