Much of the public may still believe that the wars being fought in the Middle East are to protect the US from "terrorism". This is, of course, a sham. The rest of the public, however, appears to increasingly subscribe to the simplistic explanation that the wars are just to benefit a few "evil corporations".
The wars are about more than that. The wars do have a motivation in US national security (and even the national security of EU and other satellites of the US), it's just a deeper interpretation of "national security" than what the public would accept without extensive flattery and well, lying.
The wars are about US global economic dominance. They have nice side effects in terms of juicy bones that can be tossed to allies, but for the most part, they're about keeping the US economy running. Other than military hardware, there are few things the US still actually manufactures at this point, so inventing reasons to keep the military busy is a huge source of employment. Hypocrisy looms large in the US: huge chunks of the population are employed by the war industry more or less directly, at the same time as they espouse anti-government rhetoric and vote Republican.
Even more important than that, though, is keeping a firm military footprint in the Middle East to ensure that a large and substantial proportion of oil worldwide is sold in no other currency but US dollars. This ensures worldwide demand for USD, even in the face of such confidence-destroying events as the financial crisis, and even with the US hardly manufacturing anything these days outside of entertainment and intellectual property (which two thirds of the world do not respect).
The flip side of the coin is that allowing the petro-dollar to be abandoned would be a huge boost to China and Russia, which are not the world's most liberal regimes; and arguably, for better or worse, aren't ultimately whom you want to benefit.
It's not only about money either, but about control. When Russia is ever ready to invade and annex neighboring countries, it's crucially important that the US is in a position to tank the global oil market via its allies in the Middle East, making it costly for Russia to be expansionist. Being able to reduce Russia's revenues brings more sting to economic embargoes, and allows the West to oppose Russia without risking thermonuclear war.
Wars in the Middle East are of course not about humanitarianism, freedom, or democracy - at least, not for the people who live there. They are about realpolitik; about long-term strategic interests of the US, and of the West in general. This does ultimately benefit regular people in the US and the West; even to the extent of propping up our economies; protecting Europe's freedom from invasion by Russia; and the same freedom of Japan, South Korea, and Taiwan from China. But it is ugly and awful, and much of the public would not go along with it, if the whole thing was explained to it clearly.
And then, of course, there's Israel.