It's both a matter of taste and a cultural thing. The first time I was in Seoul, a friend of mine took me to a place where they served "live octopus" with raw meat + raw egg yolk. It was extremely delicious, the raw octopus legs where still moving and twisting (just like in this example it was just nervous endings activated by chemicals in the food), they even wrapped around the chopsticks. The octoups + the yolk + raw meat provided an incredible mix of flavours and textures. I'm not Asian (actually I'm from South America), but my friend told me I already ate most than what even a typical S.Korean eats. I guess I was just more used to experience "weird" food because my family is from the country side in Chile and I also I really like to eat/try all kinds of sea food.

Going back to your comment: it's not just about making the animal "perform", I see it more as a proof of freshness. In the end is all about the textures and flavours.

So much talking about food, now I'm hungry :)