game brings in double that in ticket revenue alone. I don't know if the TV contract gives a school any extra for playing a 7th home game instead of just 6, but I imagine the TV people want more inventory and not less inventory.

if they do home-and-away, one year they make money on the series and next year the make nothing on the away game.

If instead of a home-and-away, they have a home game against a first team the first year and another home game against a second team the second year - then its two chances to make money at the gate instead of just one.