This. The first-past-the-post scheme, combined with the ridiculous financial leverage of the D and R parties serves to squeeze out almost all outsiders. Add to this the fact that by not being a D or an R, a peripheral candidate has to contend with the issue of irrelevance: why would I vote for the G or the L or the I when I know their voice will be drowned in a sea of DvR noise?
So the country get run by the middle, more or less. I am not convinced that that is a good thing. Because there are wackos out there that I would not trust as far as I could throw them, but those wackos almost certainly have areas of expertise that could be helpful for making policy decisions (the part of them that is not quite so wacky). More importantly, if those people get shut out, as they do, they become not just wackos but extremists, in which case, they can be a nuisance to the rest of us – or worse.
Really, we are losing out by not including everyone in the process. The party system and sports-like elections are not helping make this country stable, and it seems like the situation is starting to get out of hand.