The problem with "it" is the word's existing use to refer to non-person objects. One could easily interpret being called "it" as an insult, ie: this thing is not even a human.

I might not even be willing to refer to a dog as "it" in most circumstances.

Honestly though, I'm with you that it's a linguistic gap English needs to fill. Similarly, the second person plural pronoun need to be accepted as "y'all"- and I say that as someone not even from the southern USA.