Yes, it's been one of the bad "isms" for some time now. But, really, in a time of limited money and resources, it makes a certain sense to refrain from engaging in disputes around the world, especially when, in doing so, we make the huge expenditures in lives, time and money which come with military action.
The U.S. simply cannot afford to police the world. In certain cases, it should not do so for reasons not associated with the need to intelligently allocate resources. But, even setting aside the question whether the intervention in Afghanistan and Iraq is appropriate on moral grounds, it is necessary to determine whether the potential benefits of being the global policeman are such as to justify the costs.
The belief that we will create functional democracies in the style of the West in such countries doesn't seem credible. Even our ability to stabilize them is doubtful. It is likely that when American troops depart, these nations, or perhaps more properly regions, will go back to being what they have been for centuries.
The U.S. is spectacularly in debt. This will erode American power, inexorably, over the long term. It makes sense to focus on correcting internal problems. This need not mean ignoring the affairs of the world. It will merely mean refraining from trying to dominate them at all times, in all places. The U.S. must pick its spots in the future, carefully.