They choose to of their own freewill, out of the limited range of options available to us, yes.
It is difficult to imagine a world of gender equality because we don't have it. If the models had been encouraged from day one to pick other careers which were equally rewarding - gave them equal fulfillment of other traits, equal pay, equal travel, whatever - would they have picked the one that relies on selling their physical selves?
Men selling sexuality - I don't particularly like it, or the specific image of sexuality they sell. I chose my life partner on grounds other than sexuality and unless I'm mistaken research shows most women do. The whole idea of selling on sexuality perpetrates the belief that sexuality alone matters imo.
What I'd like to see is gender equality, where women and men are not judged on their sexuality except with those they choose to be. In practical terms I'd like to see women and men acknowledged equally responsible for children, equally responsible for consensual sexual encounters, an absolute halt (in ideal world) to non-consensual sexual encounters of all kinds.
How to go about it, that's the question isn't it. The chat boards are there to support women who get fed up of seeing sexism in everyday life as well as to try and find solutions. Supporting other women who think that women are valuable in non-sexual ways is important as individually we're all easily run-down ourselves and dismissed by others. There are some men on there, though it's true it's mostly women. I don't see many attacks on other women at all. Mostly I learn on there.
This is an attempted response to LyingWitch btw. Now what else has come up while i've been attempting to think? 