-I think it could be that, plus two other factors. A backlash to the older notion that many people used to have that asians were superior martial artists based on their race (the fallacy of logic that if you were of the same country of origin as an art, you or your training was inherently superior). And that generally in unbiased (wherein one group or nation does not control most of the judges) international competition, MOST(not all) of the asian competitors and teams lose pretty badly.
- Personally, I blame this more on antiquated training methods where this occurs. Hand me down (from tradition) rather than scientific research and methodology. In the cases where tradition may be observed, but is not restrictive, and the fighters and training is very adaptive, you don't see the Asian teams and competitors out of the winner's circles as much.
-Giving more thought to the previous posters mention of the western screen image of the western hero "putting the asian villain in his place", I was reminded of an article I once read years ago. It mentioned how as a propaganda tool used by the USA during WW2, one film highlighted an American hero(actor) who was trained in either judo or jujitsu and used "their own tricks against them" against those "yellow devils" (Brief mandatory PC disclaimer- the following quotations do not reflect the opinion of the poster. They are to best memory, the words of the USA propaganda machine during a time of war. So please, no hate e-mails). There might be more of that attitude left over in some circles than we would like to admit.