Ah that's possible, but it's not really user-friendly. At least not for me... Imagine you would have to do that in the single-player menu too.
I can't remember all that maps names. Esp. all the climb-maps!
And who knows, maybe while looking at such a list, one finds some interesting maps, one didn't even think about..
It as well would be nice to have some groups, like DM-maps, CTF-maps, climb-maps.. I know some are interchangeable, but there always is a predestined usage per map ... usually.