Northstar is coming back soon I thought.
However the unfortunate truth is homosexual characters tend to get written off rather quickly if you try to do something big with them (like put them in a top selling book or give them their own title). YA and Runaways survive easily because they are designed to appeal to the fringe element crowd (both are non traditional books to begin with). But X-Men, Batman, Superman and JLA to name a few attract a larger crowd and therefore have a more diverse audience to appeal to.
I think another key difference is they often don't write gay characters as superheroes who happen to be gay. They right their homosexuality almost as their superpower (on top of whatever else they do). Then the book reads like "Here is our homosexual hero eating breakfast. Uh-Oh the bank is being robbed, how will our hero respond being homosexual. He better change quick and kiss his other homosexual lover goodbye. He is here, how does the public love him....unbeknowst to them he is homosexual, should he out himself? Here he is fighting his archnemesis--did we mention he is homosexual?" And so unfortunately to writers (who may quiet possibly be straight themselves) they miss the nuance and subtlty of writing a gay character. They view the homosexuality in a very freudian light and assume it must inform all his/her decisions. Whereas for comprable straight characters, this is hardly a problem.
Some like Apollo and Midnighter, Ultimate Colossus, Wiccan and Hulkling and a few others have figured out that to write a character of any sexuality you need to address said sexuality without making it overexposed or the focus. Just as Scott and Jean's silent love for eachother in Stan Lee's X-Men wasn't the main story of that book.