This is, of course, a matter of opinion. There are arguments to be made for both sides.
On the one hand, we can argue that the US should not try to police the world as it did in episodes like the Persian Gulf War of 1991. There are at least two reasons for this. On the one hand, we can say the US should not do this because this role is too expensive. It does not, one could argue, make sense for us to spend our money being the world’s policeman while other countries do not have to spend much on their militaries because we will protect them. Second, we can argue that it is not in our interest to try to police the world. It is in part because we do try to act in this way that so many other countries dislike us. A large part of the reason why radical Muslims hate the US is the fact that it intervenes in their part of the world in ways they do not like. For these reasons, it can seem that we ought not to try to police the world.
On the other hand, we can say that it is necessary for the US to police the world. In our rapidly globalizing world, we need stability. Shocks in almost any part of the world can hurt our economy. Therefore, we cannot rely on other countries to keep the peace that we depend on for our prosperity. Since the world needs stability, and since we are the only country rich and powerful enough to provide it, we must police the world.
Of these two options, I tend to lean towards the latter, but there are clearly arguments to be made either way.