Neutron 66 and D-rock pretty much nailed it.
None of the actresses on that list have had even a small amount of mainstream success. Seriously, does anyone think that Raci Lords would have been cast in Zack & Miri Make a Porno if she hadn't been famous/infamous for doing porn when she was underage. And I'd hardly call doing walk on parts with at most two lines in an episode of Melrose Place success.
I recall reading on another board about how Sasha Grey was breaking out in the mainstream film community thanks to the Girlfriend Experience and because of it she was going to have "major roles in several major films." Turns out those "major roles" were non speaking parts as a waitress and another nameless extra.
Thing is, when female pornstar does try and go mainstream, they get only get roles or scripts in which their character is either: a prostitute or a pornstar. Ginger Lynn complained about this and said it was the main reason she said fuck it and went back to doing porn.