As mentioned before and my main argument/complaint is the lack of American runners training together. Besides a few weeks of the year, many individuals are nestled in a corner "because they like to train on their own" or "My coach and I work well together" or "no one is as fast as me." When people do train together someone will post that the reason they burned out is beause they trained too hard to keep up, which I think is a load of crap. If a bunch of people train together everyone can find someone else who runs at their pace or they can even run their own pace. Even if everyone is seperated, everyone knows that the other person is out there working just as hard. Then when they finish the workout they can all smile together. Just having someone there makes running easier and more enjoyable.
I also think society plays a part, but in a country of 300 million people, I think there are more than a few people who have the potential to compete internationally. Using Meb, Deena, Rupp, etc... to say American distance running is on the rise is just a red herring. There are only a handful of American men and women who have a chance to compete on the global scene.