But the need for them has gone down? Should we hire 10x as many? 40x?

Has the need gone down? This isn't only about fire. Where I live fire fighters are a "jack of all emergency trades" because we can't keep experts in everything on hand all the time.

I'd rather paramedics for medical problems but they don't have training to deal with all the other things that happen in an emergency so we still need others. And better than paramedics is fast transport to a real emergency room because that will have specialized equipment that won't all fit on a vehicle - which a well trained fire fighter can do.