I think one of the handicaps US runners have today is their access tot eh weight room.
I Believe its over blown. Yes you need to be strong, however strength is needed at specific points not all the time.
I always see guys who strengthen-up, over work their arm action and take away from the advantages of their legs, and hip position. If arms were really that important for improvement, we'd be on all fours. They tend to drop hips, and pull themselves down the track instead of staying high and allowing their stride to progress.
Have a look at the greatest runners from the past. Herb Elliott for example. Have a look at the Ryan video in this thread, and see where they carry their arms. Its great to be strong, but not if it adds too much weight, or changes your natural action. Shortened / natural arm action leads to quicker recovery. Keeps the hips high, keeps you over your toes. Least amount of 'braking' on the ground. Better flow.
Strength is to be used like a fire extinguisher behind the glass case. Only when needed.