I was just wondering, why...?

Why does the world have to be so closed minded on the issue of bi/gay people? I'm just wondering... I know this isn't in the right section, I apologize but asking it in the LGBT section comes out with some pretty obvious answers... I'm not trying to be mean or anything, I just want to know why ual orientation is such a big deal? How does it affect a person's abilities and how does it make them un-human? Some of the world's greatest people were gay/bi - Alexander the Great, William Shakespeare, Elton John, Ellen Degeneres, etc.. We're all humans...life's too short to judge isn't it? In the end does it REALLY matter? Is it so different as the color of someone's skin? Are we still stuck in the 1960's with unequality to that of african americans even though they hadn't done anything? Don't we still look back at that and consider it silly and foolish to be prejudice against someone for that reason? What happened to America being the land of the free? First amendment anyone?