I don't see how the majority of them last; outside of the BCS bowls and the bigger "lesser" bowls (Capital One, Outback, Cotton, etc.), it seems hardly any of them can get fans to show up.
ESPN needs programming 24/7.. the bowls live off ESPN $$$ - ESPN will show these games several times b4 next season ( ESPNU over summer,etc.) and get advertising $$$$ for a 1 time cost.