I personally don't think that years spent washing rice will improve the taste of the food, but it may give the chef an appreciation for what he's doing.

The biggest difference between sushi joints is quality of fish. Everywhere in Japan can get fresh fish daily. The best I've had outside Japan was in Tenerife at the fish market in Santa Cruz. A lot of foreign places skimp because they don't care and neither do their customers. In Japan you wouldn't want to be known as "the guy who makes crappy sushi".

In the same vein, does the Japanese tea ceremony produce objectively better tea? Probably not, but it's a ritual.