You can't just "send experts" or "leave the idiots to fend for themselves" in the Middle East. That would be nice. We're all extremely frustrated with the region, and of course America has made a real hash of its desert adventures over the past couple of decades.
But the fact is that the region is uneducated, unable to support a single truly advanced economy outside of Israel and Turkey (Iran will be able to, too, once it snaps out of its theocratic phase), wracked by sectarianism, trying to figure out what to do with all its misdrawn borders, and home to at least two countries with nuclear weapons (Israel, which might be tempted to use them against one of its neighbors but won't lose them, and Pakistan, which is much more dangerous since someone might get their hands on the nukes. As for Iran, that's anyone's guess). It's not ready for democracy; democracies need secular institutions that actually operate, countries that function as coherent units, and electorates with enough money to have something to lose if something goes south. The first two aren't true across most of the Middle East, and the third is mostly true in its absolute monarchies. The Middle East either has to deal with strongmen, who can be brutal but at least keep border stability, or it needs someone to babysit it. Do we really want Russia or China to be doing the babysitting?
Yes, the US really fucked up in Iraq and Afghanistan. Yes, interventionism is expensive. Yes, it makes enemies. But we're now seeing what happens when we remove the threat of intervention: desperate strongmen using sarin gas on their own people to try and protect their own position while a nihilistic, terrorist ultra-theocracy springs up in the vacuum and creates a living nightmare. You cannot tell the Middle East to pull itself up by its bootstraps; it doesn't have any boots.
More broadly, the current world order, and geopolitical stability, actually rely on the US being able to project force worldwide, even if it's for the wrong reasons or done by dimwitted Dominionists who can't tell Sunnis from Shiites. We've tried isolationism before. That, I'll remind you, was in the 20s and 30s.
Yes, the US is the world police. No, that's not a perfect state of affairs. But geopolitics is about the least bad possible option, not the best theoretical one. Someone is going to be world police. The EU is probably the best candidate, but it's decentralized, too pacifist for its own good, and dealing with economic malaise. Those of you who think the US should knock it off and stop playing world cop: if the US doesn't, China or Russia will. Is that really the alternative you want?
(As for the UN: the UN hasn't got a tenth the power of the US, and its structure gives Russia and China veto power over any proposed intervention. This would be an improvement?)