ok let me clarify mi stance since you also clarified yours,
my stance is gender race and everithing else, tells a reader WHAT a character is, and that what is engaging and relatable is WHO a character is
being gay is what he is, being a fun respectable guy who likes cats is who he is,
what a character is can't be changed, but Who he is can
a violent person can turn into a happy and calm person with an arc, or a situation that forces it to change.
but a hetero can't become gay just as a gay can't become hetero, or a black turning into white, the gender one is for trans storys only (I think we can agree with that), though all this is made in the sand so if some one wants to make a story of a white or black wanting to change into something else they can do it (have fun with the comments : /) also let's be cleare the this character was gay or hetero all this time, is something jarring if you don't start the story with hints to this as in since the start this person was gay/hetero or even bi.
stereotypes are a fluid they change from culture to culture, example in my culture blacks don't have this stigma of being gangsters or liking fried chiken(everybody likes fried chiken), but in USA they do, so why should I have to use black as gansters as a stereotype if my culture dosen't think that?... see what I am getting at? stereotypes are like fads they change they evolve and they are forgotten through time, before japaness where sterotyped as having giant teeths... when was the last time you saw a comic or movie with and asian with giant buck teeths.
I hope I explained myself better this time and that we can stop going in circles C:
also to your questions of why some stereotypes are for some and not for others
that's cause in this time that gender or race has done that so manny times that it became a stereotype, its a fad that will pass as people get sick of stories with that stereotype example, the Idiot father was before the Idiot mother from sickcoms of the 50 and 60, the idiot father and sensible mother was a reaccion to this stereotype so now it's the new stereotype... they change and are made of water, they aren't set in stone so go wild with them, change them, follow them or subver them. this is what makes writing fun