There are many movies and documentaries about female prostitutes. While some focus on women forced into prostitution against their will, most of the rest vaguely imply that the female prostitutes are exploited by their male customers. The message seems to be “Don’t they see that the money they gain is just not worth their loss of intimacy, self-respect, etc.?”
The ’06 documentary The Great Happiness Space (reviewed here) offers an interesting contrast. It shows the world of a certain kind of male prostitute in Japan. And it vaguely implies that male prostitutes exploit their female customers. The message seems to be “Don’t they see how much money they lose for just an illusion of intimacy, respect, etc.?” Even though many of the female customers shown are themselves prostitutes, we are expected to see them as victims.
Of course the two prostitution practices differ somewhat, according to male vs. female fantasies. Men tend more to seek simple no-strings sex and polygamy, while women more seek emotional stroking and hypergamy. But it is striking that any for-pay male-female relation portrays men as exploiters and women as victims, no matter who pays whom.
Street hookers need protection, since it's a risky business.
The person theorizing about the positive effects of prostitution on violence may be implicitly holding something like a "bare branches" theory, which is wrong.
On the incentive of women to oppose prostitution (just as workers oppose scabs) see Baumeister et al's Sexual Economics: Sex as Female Resource for Exchange in Heterosexual Interactions. I'm refraining from linking to avoid tripping any spam filter, but you can find it online.
I think that the best explanation for the length of you comment is that you haven't had a long term relationship with a prostitute. I did. It was fun for both of us. Lots of fun. It made us both happy. Happiness is a great destination. On the other hand, that could just be my cognitive bias.