I bought this up in chat earlier. It went something along the lines of:

 - Me: Why are there only 3 positions? Surely we want more than we have now.
 - Marco: Current mods aren't that active but I cope.
 - Me: True, you are awesome.
 - Marco: If we had 3 active mods, it would be easy.
 - Me: True

On reflection we do only need a few but for it to be easy as we grow, we need two or three on *all* the time. I do think five is a much healthier number but we have at least a dozen people who are trustworthy enough to have the designation... So why not?

I'm serious. Adding more only makes the job easier.