I agree in theory, but I think the convenience of not having to learn a new pronoun (ve? xe? herm?) outways the inconvenience of the ambiguous they.
People already use the singular “they”, and if anything, inventing a new pronoun draws extra attention to non-binary identity in a way I’m not entirely comfortable with, while singular “they” sounds like slightly lazy speech.
Ideally, eventually non-gendered pronouns would be as uncontroversial as using Ms. rather than Miss or Mrs, but there’s far enough to go that I think a singular they is a decent half-step.