I heard flash freezing can make the sushi taste better too. Does anyone know if this true?
Korea has a similar dish called kimbap, which literally translates to "seaweed rice", so having something other than a roll wouldn't be kimbap anymore. Also, Korean kimbap uses a different recipe for the rice (usually sesame oil and salt), so it can't even be considered a special case of sushi (rice with vinegar and sugar).
I feel far too many people don't understand what sushi is, even if the consider it one of their favorite foods.