Mod installation isn't hard for experienced people, but I remember when I was new to Glest, installing the Megapack was hell, I'd never seen the Glest folder structure, and I was so happy when I got the Megapack installed!
So yah John, I'm talking about something similar to what Wesnoth has.
But instead of on the menu, a separate program. We'd have a separate program because we wouldn't be able to get an official release of Glest with that menu addition in.