Why does fatty tuna cost more than lean tuna? Is it because some people think it tastes better?
Yes, the fatty part of the tuna is prized for its flavor, especially in Japan. They particularly like 'o-toro' tuna, so that drives the price up there and elsewhere.
Otoro represents a most enjoyable part of dining found in Japan, and a large number of bluefin tuna farmed all over the world land in typically the fish marketplaces linked to Japan, exactly where the o-toro will undoubtedly receive a more expensive price tag amongst sushi enthusiasts.