One of the things a party can do with a financial advantage like this is force the other party to spend money it doesn't want to spend. Obama doesn't need to match Romney's spending to win Michigan, but if he gets outspent, say, 10 million to nothing, he could lose the state. Republicans have the money to dump into safe Democratic states and force Obama to defend them. If it works in Michigan, it could work in other blue states, too. The point isn't to win those states. The point is to drain Obama's resources for the states he really does need to compete in, like Virginia, Ohio, Colorado, and so on.
Kornacki, on the other hand, downplays Romney's cash advantage.