Not true! In beta, we had 12v12 (or possibly 16v16) CW's all the time. They ran fine imo and were a blast! There's no reason we couldn't do larger WZ's. AH, CW and NC are all large enough for 12/16v12/16.
Just imagine a huttball map with double the people, double the traps, and double the fun. Not every pvp map needs to be 12 v 12 or 16 v 16, but man... one giant huttball would be a huge start.