I don't know if I could participate in a green card marriage or not. I think there are plenty of women whose lives would be greatly improved if they could become US citizens, but I don't know if I would be willing to stick my neck out legally to help someone gain citizenship. I don't think I could survive one of those immigration interviews proving the marriage was legitimate.
On the other hand, I could imagine a situation where I met and fell in love with a woman from another country. If I felt the relationship had some longevity and mutual commitment, then I would do everything I could to help her gain citizenship through marriage. A green card or permanent residency are still good things to have, but I'd want her to have all the opportunities US citizenship can provide.