See the companion post: Why Not to Come Out
Reasons I can think of, past and present, valid or less-so, for why I have chosen or would choose to "come out" to people (feel free to add your reasons--I'm interested in people's motivations here):
1) It's just part of me. Why should it be that big a deal?
2) How will people ever overcome their prejudices if their closest friends and loved ones do not reveal themselves and open up?
3) Why avoid the issue just because it might test the relationship? Why not find out how true your relationships are?
4) There's something liberating about allowing people to know the fuller picture, the more complete puzzle, and discovering that they accept you for you, even if they don't understand, and allowing them or helping them to see past labels.
5) Sometimes it's helpful to other people for them to know your life isn't as perfect and cookie-cutter as it appears.
6) Get people off my back when it comes to asking about why I don't date, why I'm not seeking the ultimate goal in life to find an eternal companion and make babies.
7) Until those of us who experience this speak up for ourselves and stop silently letting everyone else grasp at straws, progress towards understanding will be entirely too slow, and those who feel alone will continue to feel alone until more people speak up.
8) It sure would make strained relationships with girls easier sometimes.
9) I wouldn't have to make up excuses for why most of my wardrobe is Banana Republic-style and why I love Project Runway. (OK, so I don't make excuses. It's more fun to just let people wonder.)
10) There's something to be said for just being "authentic" and "genuine" and welcoming the same from others. Doesn't the world need more of that, in some ways?
11) I don't want my mother holding out hope that more grandbabies are just around the corner. There may be, but right now, making babies is not on the top of my list of fun things to do with myself.
12) If they knew you were dealing with this before making any apparently drastic decision, it could soften the blow when you do decide to date a guy and have a relationship, rather than looking like you suddenly decided you are gay and went off the deep end.
13) It's nice just to have a little sympathy sometimes, or understanding of why you're not always chipper or as "faithful" as others think you should be.
14) You don't have to hide your copy of In Quiet Desperation in the back of the closet with your porn. OK, so I don't have porn. At least not in the back of the closet.
Note: Stop freaking out, reason 14 is a "funny".