You say "the rest of the alphabet" but mist of the groups represented by those extra letters seem very quiet. Is there a significant movement of asexual people demanding 'rights'? Or 'two-spirit' people? Or people with DSDs?
Or is it trans activists and queer theorists making nearly all the noise, and co-opting IA2S+? With queer theorists being those who for some obscure reason want boundaries to be blurred and norms removed ...