I keep telling people this, because it can't be emphasized enough: The reason your choice in the general election is between a giant douche and a turd sandwich is that those are the people who win the primaries. If you want to change that, vote in the primaries.
Perhaps I'll be "throwing my vote away". Nonetheless, next time around, I'll be choosing from amongst the other choices.
For the Federal elections, it's early enough in the cycle that if people start doing this en masse, it might have some real influence.