Very good idea Rap.
I play between what would be prime time evenings (6pm - 10pm ish MST). Without question these large maps are a real wet blanket at these population levels, even during these peak population times. The uber-maps like the current one don't even work well in peak times with 300 people online. they're just so big that even that level of players is the very bottom of the required level needed to make gameplay flow.
However what makes them much worse is that their extreme size means they can't be conquered, so they stay until they timeout. Makes for long painful periods where gameplay goes into the crapper. Worse, the smaller maps that encourage the very activity you want to see (furballs, lots of activity over small areas with base taking, etc), roll much faster and thus push us back into the uber-maps.
So rather than keeping more of the smaller maps in the rotation more frequently, we have these uber-maps just sucking the life out of the gameplay for extended periods of time. It really is brutal, which is a shame because the game is a blast if you can get onto a smaller map.