I dont agree with Benny, certainly on the moral position, but sex worker advocacy groups like the scarlet alliance cannot, by definition speak for the hundreds of thousands of women forced into prostitution. For every German or Australian sex worker who controls her own income and terms of employment, there must be dozens who are trafficked and effectively enslaved.
My default position on most of these kind of issues is 'let women sort it out', but there is a valid argument that many women involved in prostitution are effectively voiceless, so from that point of view I don't see any major problem with having these conversations as long as they are non-proscriptive.
It's a difficult one, with loads of opposing but valid claims... ...regulation seems like the least worst option to me, but I can sympathise with other POV's.