You make some good points, but I think my answer to the question in the poll title stands. English already has a genderless pronoun.
Many people dislike it, and in some cases it may be ambiguous. But I can't see English using any of the suggested alternatives.
You prefer using he for the genderless pronoun. It does have some history, but I think it also has the insurmountable disadvantage of being sex-biased.