I found your question offensive, or perhaps at best worded badly... The blame for this may in part be my own, but you're the one who typed it.
My profile could also say I was from outer space, my sexuality has been explained within this very thread had you cared to read the entire thing.
Do you feel uncomfortable when you can't easily label those with whom you speak? /emphasis added/
I think this vexes many people,
Aconitum... without a label, they don't have an ability to judge you, to automatically like/dislike you or to place you conveniently into a bin with all of the others 'like you' before they've ever met you. In my opinion, this is the problem with labels in general. A label removes the necessity to actually converse, explore, and then decide whether or not another human being is of interest to us.
If I were King for the day, I'd remove that little box on the LPSG profile for sexual orientation because the gender of the person we sleep with has so very little to do with anything else. Others may decide I'm in denial or hiding or (pick your favorite judgmental phrase), but for what it's worth, I'd also prefer that we did away with political parties and instead, voted for individuals on the merits of their ideas rather than their association with a particular group of people or an ability to pander to a particular bloc of voters.
The political party analogy is a good one: I do not automatically dismiss people who identify themselves to me as "conservative", "Republican", "Democrat", "liberal", or "Reagan Democrat" simply because of their self-identification... I want to hear what they think and why think it. If I rigidly refused to talk (for example) to conservatives, I might miss a meaningful conversation or idea that could shape my own beliefs. I won't likely decide 'wow, now I'm a conservative', but I might be more sympathetic to conservative principles in the future. However, I'm a rarity. Most Republicans won't listen to a Democrat (and vice versa) except for the opportunity to argue with them. The label -- in my worldview -- gets in the way.
It's unfortunate, but I think there are a lot of conversations that don't take place on this site simply because of that sexual orientation tag. I think it's fine for people to self-identify if they wish, but I do think your original premise is an unfortunate commentary on our society: we need labels to make ourselves comfortable.