I don't know other countries but in Japan, if you are the first Japanese and "wins a medal", then you're pretty much shoe-in for the selection for the next Olympic marathon team. That's how Noguchi got selected for Athens (winning the silver in Paris). That way, you prove you're a championship contendor, run well in the heat, and then have a full 12 months to prepare for the Olympics. That's what Ogata wanted and that'w what Tosa wants. I remember in 1995, Steve Plasencia finished 10th at the WC marathon and then finished 4th in the trial. Naturally, he felt he should have been picked by having proved that he could "compete against the world in the summer marathon". I agree. In a way, he proved that he could be competitive. Unless there's an incentive like that, it would be hard for the top US runners to want to go to the WC over some big money race in the fall. In fact, I think the US should consider races like Fukuoka to be a part of selecting races; it's oversea race (it's same Asia for God's sake...), very competitive... In other words, it's a great place to prove your worthy of being internationally competitive.
I'm not all against one-race-only system. Don Kardong is a good friend of mine and, if it's not that system, he would have never gone to Montreal and finished 4th. Actually I feel the same way (in a way) with Ritz. Sure he has not proved he's competitive in the marathon but, if everything goes well, he's talented enough to be very competitive anywhere. Can he and his coach prepare himself enough to be that level is yet to be tested; but remember, Frank Shorter's PR, going into Munich was "only" 2:12. He was fast on track; he went to Japan and ran Fukuoka (oversea, competitive) and prepare himself for the Olympics. He didn't have to have run 2:08 to be "topic of the message board" to become the Olympic champion.