This is an extremely simplistic and dangerous generalization. Teddy Roosevelt articulated the most sensible approach to foreign policy when he said we should "walk softly and carry a big stick." We cannot possibly control the entire world. It's typical American jingoism to think we can. At best, we can make nations who antagonize the ointment of world order pay a heavy price. Even that has its limits. World domination and control is completely out of the question.
In the war on terror, we have embarked on nation-building escapades in two countries: Afghanistan and Iraq. We are already spread too thin and we haven't yet taken on the greater long-term threats to our security. We are hoping against hope that North Korea and Iran will acquiesce based on what they saw us do to Saddam. We'll probably end up paying the North Koreans for a nuclear-free Korean penninsula. We likely have no choice but to accept a limited nuclear capability for Iran. That's hardly what I'd call "control."
We are the world's largest economy. But, relative to the economies of the rest of the world, we have been shrinking for decades. So economically, our power is actually diminishing over time. This may be a good thing as markets open up for our goods and services, but it gives us diminished clout in terms of our ability to dictate economic matters to the rest of the world.
Militarily, we are way out ahead, but military advantage has its limitations. At most, the military can be used to facilitate a stable environment for global trade. It can't realistically control the world.
Generally, neocons tend to accept and promote the role of America as keeper of world order. To claim Reagan as a standard-bearer for their philosophy is somewhat of a stretch, since Reagan tended to shy away from conflicts in which we had no compelling national interest. Reagan cut and ran in Lebanon, which may have been the first in a string of actions that led the terrorists to conclude we were weak and indecisive.
As far as government spending is concerned, Reagan supported tax cuts for the two-fold purposes of limiting politicians' ability to spend and stimulating the economy. Today's neocons simply cut taxes and increase spending, which makes them bigger panderers than the liberals, and fiscally more irresponsible than any political ideology on the scene today.
Yes we are. But as most Romans had no say in what happened in their Empire most Americans don't either as both parties will support our current policies to one degree or another and our modern vote is near wothless as compared to the Roman vote. By the way - there were many members of the Roman forum who were against Roman Imperialism and for the Republic?