If I don't eat the bunny, I'm sure to find something else to eat. If I eat the bunny, though, it's definitely not going to be alive anymore (attack of the zombie digested bunnies anyone?)

There isn't as much pressure on human evolution to avoid making cuteness mistakes, as there is on bunny evolution to be cute. If evolution were to move fast enough, and the cuteness complex would be hackable, it seems possible to me that things would evolve to hack it (and beat out babies at it).