A friend recently asked for my thoughts on this question, and this was my response. I certainly can't speak for people with same-gender attraction, but I have had a few thoughts about what happens when we talk about them in these terms.
Sure, the alcoholism comparison works to the extent that it implies the homosexuality is biological, but it breaks down pretty quickly. A couple of reasons for why I wouldn't use it:
1) When we're talking about homosexuality, we're talking about a totally different sort of desire than what alcoholics have. Sexuality is, for better and/or for worse, a key motivation in much of our decision making and much of the way we interact and relate with people, especially people we love. Like you say, it's different than alcoholism in that homosexuals have the urge whether they've "tasted" it or not, but, to take it step further, we're talking about a drive inherent in the human experience and the propagation of the human species. Sure, it's problematic that homosexual sex doesn't serve an evolutionary purpose, but that doesn't change the fact that we're dealing with a much more powerful, inherent urge than a strong taste for alcohol. It's also important to remember that while we believe we will overcome all temptation eventually, our sexual desire is not ultimately thought of as temptation. It can be a source of temptation, but more fundamentally, it is a power to be harnessed and expressed within the bonds of marriage, not suppressed indefinitely. No one is encouraging alcoholics to settle down and find a person with whom they can appropriately express their alcoholism.
2) I'm also hesitant to use the analogy because of the more subtle impact it has on dialogue (internal and external). It is a very divisive way to talk about people. It might be helpful for us to conceptualize why gay people do what they do, but alcoholics have a problem (and can usually admit it). They know that alcohol clouds their judgment, ruins their relationships, and so they try to quit. Homosexuals--especially outside the church--have nothing telling them that what they're doing is hurting themselves or other people. We're telling them that they're living "inebriated" so to speak. While alcoholics tend to be incapable of being upstanding, productive members of society, that is absolutely not the case with homosexuals. Some of the most talented and inspiring people I know are gay. This is all a little heady--it's not like this all runs through people's minds when the alcoholism comparison is used--but using analogies that alienate people and describe them in terms they certainly would not use to describe themselves only creates distance and derisiveness. When we talk about homosexuality like a disease and then try to make laws that limit the people who have it, why are we surprised at people who picket the temples or make vitriolic attacks on the church in the media? I'm not saying the Church didn't make the best decision it could have made with Prop 8--honestly, I think its most redeeming consequence is the fact that we and others are having this conversation--but until gays and church members are talking about gayness using the same terms, we'll never get anywhere.
Honestly, I think all the analogies are a little dangerous, because they all break down at some point, and they're all a little condescending. I've heard comparisons to alcoholism, people who'll never marry, handicapped people, drug addicts, etc. But, again, we have to think of what speaking in analogy does to the way we think about people and how they would react our speaking about them like that. Who wants to defined by analogies? Who would want to be categorized and discussed in terms of someone else's problems or tendencies? No one would. I'm trying to imagine how I would feel if someone said, "Bryce's tendency to be a passive-agressive jerk is analogous to (insert negative stereotype)..." Sure I can use those analogies when I talk about myself, but when other people start trying to fit me into some conceptual box, I'm going to get a little defensive. We all want to be known and treated for who we are. Sure, the church has to make policies and delineations and limits, but you and I don't. We just need to see homosexuals as human beings and treat them as such.