It's about the appeals of sexuality and the aspects of sexual organ that makes a gay man become aroused by a cock.

Consider how women look at dicks. Many of them will not find an erect penis to be very attractive when they're the type of woman who bars herself sexually (prudes, monogamous, etc). However, when a woman becomes far more open to sexuality, it is common to look at the penis as more attractive. They'll even be more inclined to want to do more things with it... you know, orally ;)

So think about being gay. If you're a man, you usually love sex a shit load. Treat it very physically. Gay men aren't much different, and now that they're gay and open about it, they'll usually love dicks... like, a lot (sometimes even more than most women).

Congrats, Joe, you are a heterosexual male.

There are lot's of people I look at and wonder why anyone would tap that under any circumstance - but people do. I've concluded this is simply a matter of personal preference, one I can accept because if all males and females based their sexual preference on the values of heterosexual males I think I would find myself striking out, forever.