A Linguistic Curiosity

Such words as 'poetess' and 'actress' are falling into disuse: the grammatically masculine 'poet' and 'actor' are now used gender-neutrally for both sexes. Why then the stink over the gender-neutral use of 'he' to cover both males and females as in such sentences as in 'He who hesitates is lost'?  If there is no objection to applying grammatically masculine nouns to females, why the objection to applying the grammatically masculine pronoun 'he' to females?