What would this accomplish? To get better, you have to play the best teams available. For a D1 school, this is a no win situation. If they win, they are only beating up on a weaker team and not getting themselves "ready for the real season" and if they lose, they get embarrassed and ridiculed for being a weak team that can't even go down a division and win.
The opposite is true for the D2 team. If they lose, they weren't supposed to win anyway..... it's a bigger, stronger school. If they win... wow, look how good we are, we beat up on an upper division school.