DDO's TR system makes a progression server obsolete. You dont have to start a new server to make old content relevant again, because it remains relevant whenever you TR. Because people are always TRing, there's always an at-level playerbase for you.
Plus, the game - especially Heroic - is so damn soloable, there's less "need" for a very broad playerbase at every level.
Third, even if they started one, you'd probably be the only one on it, which would defeat the purpose even for you Who'd want to give up all their progress, all their server-only unlocks and purchases, just to get to start over from scratch on a server with no resources, no economy, and no twinking allowed?