I wouldn't see why I would ever want to change.
The advantage for being straight is that there is little cultural backlash/shame on it... so I could see why many gay people would want to be straight.
In fact, for those reasons why wouldn't everyone want to be straight?
I could see the bisexual argument... that's probably the best sexuality to be if you are truly bisexual.
But why on earth would anyone WANT to be gay????