Yeah, same here. I would think the G5 program makes more from the payoff than if they had a home game. More money and getting thumped in the relative obscurity of the P4 stadium instead of in front of your home fans seems like a win-win.I don't really believe that G5 prefer not to host a big name program to come to their stadium, however since the motivation is for monies received than it may be better financially to take the payoff.
Since I am not privy to these negotiations, I am making an educated guess, and would not presume that I know the definitive answer.
East Carolina pretty well built their program in the '70s, '80s and into the '90s by going on the road and playing bigger programs for homecoming or OOC games. They became a dangerous team because the revenue they received and the exposure helped them recruit better than the other teams in their conference. Southern Miss did the same thing. I remember Frank Howard saying he would never schedule East Carolina or Southern Miss because they were two teams that would come in and beat you at home on homecoming.