If you're using Drupal, there is not doubt in my mind an extension that would allow people to upload their own files. I can't play on the main server right now because it has maps that I don't have, and I can't find the link to download them at.
I assume Rawhide 1.1 is still the main server. And if so, any custom maps that are on that server should be readily available on this site, or else new players will be quickly deterred.
Specifically, once that portion of the site is made, the message when someone gets kicked from a server should not say "missing file xxx.bsp", but it should rather say "You are missing xxx.bsp from your baseq3 directory. To retrieve this file, please go to www.smokin-guns.org/downloads
Or, even better, directly allow people to download from servers. Perhaps back when WQ3 was first made, this was not even a possibility, but this is definitely something to be given thought in this era of computing.