That should be reason enough, but as a bonus reason I am really weary of the two-party system. Some people have claimed Romney was just "Obama Lite" and that the two are basically the same. I don't go that far; I see a lot of differences between them. But I do think there are a lot of other ways to combine social and fiscal stances than the combinations the Democrats and Republicans offer, and I think there are a lot of people who wish alternative combinations were viable options.
I think this quiz sort of gets the idea. Instead of a spectrum of Left to Right, it adds a second dimension. Check it out, see where you land.