The issue for me, which keeps me off TNR servers is the games I play right now:
FFXIV
NHL 11
Black Ops PS3.

I'm one of those who tends to donate when I am playing on the TNR servers, but I don't when I am playing other games. I know it's not a solid answer, but maybe some insight into why the TNR server pops are low. People moving on to more modern games, and for me console gaming has taken a seat.