When I was in college, I thought I had an original idea: everyone should be allowed to make out with whoever they wanted on the condition they also made out with whoever wanted to make out with them. I thought it was a fair exchange. It turns out Aristophanes had the same idea in 390 B.C., so it wasn't as original as I thought.
Still, when I suggest this concept to people, it is as unpopular as science in Oklahoma.
The reason is, I think, that there are lines we don't want to cross, even in exchange for some great benefit. We don't want to kiss people we don't like, maybe because it changes who we are. By kissing Sally, I become "someone who kisses Sally" or "one of the people who kiss Sally" and that sticks with me. And maybe I don't want to be one of those people, for whatever reason.
Kissing friends changes the friendship. It acknowledges a reciprocal sexual dimension to it, and for some people, it's too inaccurate to even pretend or there are insecurities about the degree to which it's really there. Even though these changes are all in your head, they're part of the kissing experience. I could advise you to ignore them and indulge, but the weird ephemera around kissing is what makes kissing fun, it's not just the tongue rubbing. So if it gets too much or too weird, maybe you're better just being friends.
The Panel: Heather, Gun Street Girl