I think it's easy to see that the VAST majority of people agree with this. (Current vote is 18-3 in favor of smaller maps) I've played a good bit of NA2 as well as EU2 because I was Fallen. The big maps are great on EU servers because there are so many people. Think about it like this.... If you have a relatively large map with 25 people on each side.... it's pretty easy to defend 3 points. The flag, maybe the wall/gatehouse, and another entry point. So the long walks between those points aren't really that big of a deal because there are enough people to at least cover them and delay the attackers.
However take that same map and play it with 18 people...... That's generally how many I see on NA2. Now you have 9 per team to cover three entry points that are stretched out over a very large map. Typically it's impossible for the defenders to cover that large of an area because there isn't enough force at any given location to do anything. So what generally happens is either A) the defenders try to hold various points like the gatehouse and a single guy can easily ninja the flag or B) the more likely scenario is that everyone just camps the flag.
Another problem is the re-spawn aspect. Large castle maps on EU are fun because no matter where you respawn there is a legitimate fight close bye. However on NA2.... it's nothing more than a pain. You respawn in this huge map.... the entire fight is typically taking place at the flag... it's just flat our boring. It's a chicken and the egg thing. People don't play siege because there aren't enough people to actually make it interesting.