Okay, so here's how I'm about to roll.
I think we are given just enough about all the characters in each film for the viewer to fill in the gaps, I like that, but maybe you'll call that lazy film making or writing or something. Here's how I took the Reeves character. It seemed to be common rebellion, and perhaps prostitution is extreme, but the film, as Melvil has said, draws attention to just how extreme it is, it doesn't want just the heightened sense of reality that occurs in Out of Sight, it wants something more, and the bisexual prostitute works well for that.
Conversely, Clooney becomes a criminal for the challenge and because he's clearly disgusted with the establishment, apparent in his scene where he goes off on Dick.
It's all mostly irrelevant though, the why in both films is not supposed to be spelled out because both films invite the viewer to observe, not interact or escape.