Some chefs think that a lobster is just a big sea roach, so its feelings don't matter.

Annoying kitchen nerd interjection:

Lobsters actually lack the neural anatomy to feel pain, and the twitches you see are merely reflexes. They also don't scream when boiled. Any knifing is a mercy kill for the feelings of squeamish cooks.

That said, I don't really eat them because they are big sea roaches.