Okay. We only need one set of gendered pronouns. Using words from one set for some people, while using words from a different set for other people, is subject to arbitrary interpretation and therefore vulnerable to othering.
Which set do you think would suffice?
"It said it would come tomorrow" means "He/She/It said he/she/it would come tomorrow" and it somehow works :) You're to infer the gender from context.
Royal We was forced, but in widespread use. This pronoun is an offshoot thereof. And other languages have even better pronouns than English. Check Chinese and Japanese.