I agree with you that Double elimination favors the better players (at least mathematically). Furthermore, by favoring the better players, you will definitely increase the chances of identifying the best player. However, this in itself need not be the primary goal of EVERY tournament.
For instance, a tournament director may want to do things to promote parity (random draws, single elimination, short races, etc...). By doing so, he may be able to maximize participation and/or dead money.
However, for a WPA ranking event (and certainly for world championships), it's hard to argue that the primary goal should not be to identify the best player. So in these events, it would probably be better to see double eliminations, seeded draws, and longer races.