I still don't see the need to be an isolationist nation.

I guess that providing our allies the goods, services, protections, medicines and security they need to survive, in exchange for trade agreements, information technologies, and intelligence sharing makes us a nanny to the world?
You think the world hates us now...? Wait till we get some moron in power that want's to remove our troops from s. Korea, Germany, Afghanistan. The resulting effects on those countries economies and security would be devastating. Crashing our allies' economies, and providing them less security is no way to extend the hand of friendship. In some instances, genocide could be the result.

Just wait till that same moron decides to let states make-up their own laws contrary to the laws of the US. Every other state on the southern border could decriminilize illegal immigration, others could force socialized medicine on us, while still others could make individual trade agreements with foreign scum.
We are 50 united states, (give or take a couple) not 50 united (yet autonomous) countries.

Granted, the Republicans often sway a tad from their root principles. Each party does, depending on the pressing social, geo-political, economic issues inherent at the time. Were they so inflexible, they would simply be marginalized party along the same line as the Libertarians.