well, "some bantu languages" do, not entirely all.
also, gender is a bit of a shaky concept, because the borders between g-aspect and c-aspect can blur pretty horribly.

>Being a silly native English speaker I think the whole idea is silly.

How so? Your language has plenty of gender floating around.

>* What makes a bus or a pair of pants have gender?

the fact that (in your language) nouns select gender in order to collect n-aspect, which allows them to be nouns while sharing their root with words of other classes.