Hmmm, good question. Maybe it's just that they are so useful and dependable and can develop loyalties like dogs and cats that many people feel some affection for them. You tend not to eat your loved ones...which reminds me (about to follow is heavy satire):
Why are people so special that we cannot slaughter them for food? I mean at the very least we can recycle dead bodies after we harvest them for spare parts. After all "
Soylent Green is People!" Although I always wondered why they waited for the old tough and stringy ones to die off instead of harvesting the the tender juicy ones.
(NOT) Seriously, I don't get it.