It's lazy and misleading to place a film in the category "Lesbian and Gay" unless it is porn. The recent film, "Brooklyn" was not listed under "Straight and Asexual" so why does a film that happens to contain gay characters have to be advertised as such?
For example, "Tangerine" is a film that is incidentally about transgender folk and will be of interest to anybody who likes honest, raucous films about the tragedy and comedy of urban street life. To promote it as a lesbian and gay film could easily put people off watching it if they were to jump to the conclusion that it is a gay skin flick.
If there is no distinct "straight" movie category then the existence of a gay and lesbian movie category is either discriminatory, if it comes from a straight classifier or exclusivist, if it comes from a gay one.
You can keep your gay film festivals if you must but once a film is out there in the general marketplace let it speak for itself.