I would like to see both of these as well. However, being able to add an unlimited number of teams would probably really mess with the game's Dynasty scheduling algorithm (which already has problems once you get a few years in), and would (in all honesty) probably be VERY difficult to implement. If EA managed to find a way to do this and make it work, I would actually be VERY impressed!
Having FCS teams and allowing them to be imported into dynasty mode, however, should be a trivially simple feature to add, as it was present way back in NCAA Football 2004 on the PS2 (maybe even earlier). Either EA is too lazy to add those schools, feels that there isn't enough room on the game disc to contain all the art assets (it would definitely fit on a PS3 Blu Ray), or they might possibly have some sort of licensing issue that is legally preventing them from using the FCS schools.
I would guess that this is probably related to the rivalry structure of the game. The scheduling algorithm is supposed to be set up to make sure that rivalries get played every year. So if you start removing one team in a rivalry, you're going to break the scheduling for EVERY team that was a rival for the replaced team. In my opinion, the custom conferences in NCAA 12 are a great idea, but are horribly broken (read my full opinion in my review at
http://www.megabearsfan.net/post/201...des_conference). Without any way to create new rivalries to replace the ones that become orphaned, EA's scheduling logic is just broken.