Why shouldn't it also be about cruelty? Tell me, what is the crueler? Nearly beheading a cow at a slaughterhouse and killing it almost immediately, or shooting a whale in the back of the head with a harpoon and watching it suffer, panic and struggle until it drowns on its own blood more than 20 minutes later? If cruelty is the reason to further agree with me, I will accept that application also.
Deer have it worse. They typically take a shot or an arrow and then wander till they die.