"tolerence": how much (or little) deviation from the "ideal" will affect attractiveness. A xenophobic faction would have mostly positive tolerence values, while a xenophilic one would be mostly negative.
I really like the idea here, because naturally (though not guaranteed) people will be attracted to people of their own kind. We've never had any real world experience. But I would think the whole "falling in love with aliens" theme you see in movies wouldn't be the case in real life... and I don't know if the equations are right, but they sure do look good to me!
As for the OP, I don't want to see this eliminated at all. I only hope they can get it right enough to even make "attractive" people (not to mention unique!!). I'm not concerned about there being ugly people, I'm sure there will be plenty of those lol making attractive people, especially because of what GW said about "eye of the beholder", is the real problem I think the devs are going to run into.