We as a nation like choices, you don't only eat at the same 2 diners, (ok some do) or goto the same one that serves only chicken or fish.
we grew from just having McDonald's to the choice of that or burger king then even that wasnt enough, so along came Wendy's, rally's, etc.
We grew out of a single ruler to a free democratic system, so shall we grow past this bipartisan lack of choice.
Then the question is why are so many against or afraid to try to eat at a political plate elsewhere?