You don’t chew ice cream, you spoon it into your mouth and enjoy the melting sugary sweetness. Now picture that with texturally soft chunks of crab. Bleh! Might as well have rotten milk with sugar.
Well, perhaps. “Sushi” to me denotes anything served atop a type of vinegared rice. It can be cooked or raw. There’s plenty of common sushi out there that has nothing to do with raw fish. (See tamago and unagi sushi for ones that every sushi joint in America should have.) I don’t think I’m being particularly pedantic on this point–people have California rolls and stuff like that when they go out for “sushi.” It doesn’t have to be raw. I mean, here ya go, chicken sushi…cooked.
Regardless, the raw version in the form of sashimi exists.