"As things stand now, no one is going to pick a real fight on American soil."
This doesn't just magically happen, though. It's because we engage threats abroad before they are able to reach us here, and because we retain the ability to respond to an attack anywhere in the world, which acts as a deterrence. You want to give up both of these things.
"Frankly, it's annoying to have a thorn in our collective side in the form of a Latin American dictator. Besides, there's nothing wrong with a Grenada, Panama, or Haiti-esque war every once in a while if the situation calls for it."
Do you know why we invaded Grenada? It wasn't because the Grenadines (?) were planning to sack Washington. It was because they built an airport we thought was too big for their needs and was really to service Soviet bombers, with some talk about protecting American medical students thrown in too. We did not invade just because there was a Marxist coup there. The revolutionary government, in and of itself, posed no threat. How could it, in a country with a population the size of a small American city? If the same thing were to happen today we would not even consider invading, since there is no superpower foe for the new government to be a client of.
Panama literally declared war on us in 1989, so intervention would be justified under anyone's views. As for Haiti, I don't know what war you're talking about. The closest thing to a war there was way back in 1915 or so. The 1993 and 2004 interventions were really just poking in to influence who was president, exactly the kind of "fingers in all of the world's various pies" thing you should oppose if you're being consistent. Again, you're just an imperialist who wants a smaller and more brutish empire.
"I have less faith than you do in the capabilities of the Japanese and Filipino militaries when they have 2.2 million Chinese soldiers headed straight for them. Besides, who's going to launch a serious conventional attack on Western Europe?"
How, pray tell, do the Chinese get there? They still do not have a blue-water navy, really. The Philippines, Japan, and South Korea could hold their own with the Chinese navy in a limited conflict, and with American involvement conventional victory becomes virtually certain. You just have a chauvinist view of the Asian powers, which is easy to do when you haven't looked into the issue.
As for Europe, there certainly is no conventional threat. But that doesn't mean they could keep on not having militaries in the absence of free riding on America's. For example, if Spain didn't have the total support of the United States in the event of an attack do you really think Morocco wouldn't make a go for Ceuta and Melilla? Even if it's not likely, Spain would have to take up the slack now carried by the United States and expand its own forces to deal with that potential threat. And who's to say the conflict wouldn't come from within Europe? Hungary has territorial claims on all of its neighbors and a significant nationalist movement that supports reclaiming them. Even if conflict stays unlikely due to the EU framework, all its neighbors would have to increase their militaries without the existence of an effective NATO putting them all on the same side and making war impossible. Hell, Greece and Turkey have almost gone to war while in NATO over Aegean disputes, without it war is almost certain in the long run.
Again ,you really just haven't thought this out. And again, that's fine. You and I will never be in positions of power deciding how the world runs. But for your betterment you ought to look at things more closely and with more recent information.