It seems like though it was used as gender neutral only for undefined gender. So if one knew for a fact that a given person is female, "he" would not be appropriate anymore.
Yep. But the gender undefined pronoun would be the male pronoun. So while semantically it would be gender neutral, from an overall perspective it's still male-centric. And we might want to have a way to refer to humans in a completely gender neutral way without ever having to explicitly specify it.
But still, I guess using 'he' as a universal pronoun would be the most elegant solution. Although you can imagine some not liking it's historical baggage.
