Beauty is in the eye of the beholder. Some people prefer blondes; some prefer brunettes or redheads. Some people prefer white chicks; some prefer black chicks. Some have no preference at all. Things like tattoos and piercings can be an automatic turn on for a lot of guys (especially rockers), but for other guys they can be an automatic turn OFF. What I'm trying to say is that it's very hard for the porn industry to find women that are going to be hott to every single guy. I'd say Tori Black is the best example right now of universal beauty within the porn industry. She's not too skinny, but also not so curvy as to turn guys off. She's got a pretty face, but nothing overbearing and her tattoos and piercings are rather subtle.
All that being said, I think they can back off on the looks a bit because let's face it; us guys aren't picky. :1orglaugh In real life, I try not to be too picky when it comes to looks. Most guys nowadays have no racial hangups or anything like that (except Revamp :1orglaugh ). Also, fewer and fewer guys seem to have weight-related hangups.
As far as performance goes, they can chill back on that one too. Most guys are happy seeing a girl give a blowjob; they're not porn critics that are overanalyzing the shit. Of course, every now and then the industry comes across an actress that is a truly great performer. Take Jenna Haze and Alexis Texas for key examples.