There are at least two reasons, other than those having to do with the economy, that WWII was "good" for the US.
First, the war made the United States the undisputed leader of the "free world." This was, of course, partly due to economics. But it was also due to the fact that the US was the sole remaining major power other than the Soviet Union. Countries that feared communist aggression naturally gravitated towards the US. This allowed the US to have firm control of the international system after WWII.
Second, the war helped to remake the society of the US. One of the major ways in which it did this was through the GI Bill. The GI Bill helped create a much more middle-class America with a high quality of life. Again, this was partly economic. But it was also due to the fact that the GI Bill helped many people go to college who otherwise would not have. It helped people buy their own homes, creating our modern, more suburban America. It helped move most Americans away from having to do hard physical labor to earn a living.
In these ways, WWII was "good" (never forgetting the terrible toll in human life) for the US both in foreign relations and domestically.