If you worry about killing grass and plants, shouldn't it bother you that your chickens are eating it?
It's pretty much the same principle; it is part of it's potential life cycle to be eaten, much like worms will probably eat you and I at some point. I can ensure them an excellent life, a swift and humane death, and a meaning for their sacrifice, which in my eyes is a lot better way to go than spending days, if not weeks, suffering tremendously as my body shuts down because someone wouldn't ease the pain. It's certainly what I would prefer for myself.
I may cull before they get to this stage, but as I said, their life is full, and their death is as painless as possible, and their memory and sacrifice is celebrated as we appreciate our meal. I don't think this is so bad, a lot better than (and I'm not saying you are one, just that these people are being hypocritical) the people who are aghast I can eat something I raised and prepared, but still eat commercially produced chicken. I can't stomach eating something that has suffered it's entire life and was killed in conveyor belt fashion, I'd much rather eat something I know didn't live and die in misery.
ETA: There's a difference between hope, and turning a blind eye. Some situations require hope. Some situations require action. For example, this fall, I found a garter snake that had been hit by the tractor next door, and was severed in half, guts hanging out, but still slithering, albeit slowly and erratically. There's no amount of hope that was going to fix that; snakes don't magically regrow spine and organs. Should I have just sat back and hoped for the best? No, I did the responsible, but hard, thing, and ended the clear suffering.
