Trafficking and abuse is still a big problem in Amsterdam. There's no magic solution.
(There have been several studies evaluating the effectiveness of Dutch regulation, but comparing the relatively accurate numbers from the Dutch police force with the guesstimates from countries where prostitution isn't legal, means that conclusions are pretty soft).
However, there's a huge advantage to a legal transaction in that if something goes wrong the wronged party need not fear going to the police. It's much better for disputes to be settled in court than by violence.
tackling this as a commercial sex issue debilitates avenues for addressing labor rights issues.