I've asked a similar question in the past and here's what i remember:
- There used to be a rotation server(s), but they didn't work as well as the current servers. Mainly many members used to leave after a map changes, and it was difficult to get consistent rankings/populations.
So in the long run, it would take much more effort and work to keep rotation servers alive and active. In contrast, many of our current servers are usually filled, mainly because the maps are the same and the players come for them.
Personally, I'd like to play on orange maps or my beloved flash. But i don't think they can survive in the short run...not now at least
I believe, currently, the events are the next best thing to a rotation map. They're meant to add a diversity to the maps offered. And from I recall, there are different times, so that European players can play.
Of course, this is my personal opinion on the matter. If i get something wrong, please tell me
Offtopic: hurray for more Canadians

(I am a Montrealer)