It would destroy the bowl system which people seem to want to keep. And
I think the G-5 schools, at least the better ones, want to not separate themselves from the P5 schools (as if that has not already happened). Such a tourney would make the most sense if we just split the G-5 and P-5 completely, and I think many would see this as an undesired step in that direction. If (or better when) that split occurs, I think it will be at the instigation of the P-5, not the G-5. Although, I agree with you that such a tournament would be in the best interest of the G-5.