Yeah, I've never encouraged nor condoned dogs doing that sort of thing. That particular dog wasn't allowed to leave the fence without being on leash, just because her prey drive was so high...even though we lived in a rural area, it wasn't cool to just let the dogs roam.
I don't have dogs anymore, but my last dog (different dog,GSD/border collie mix) was well trained. I could walk her off leash anywhere...you could see that she wanted to chase animals, but wouldn't do anything without permission. The few times she did start to run, she could be recalled easily. In her case, I think it was more of a herding thing rather than trying to kill animals.
I did have one incident where a doe jumped inside the fence that I didn't know about. My dog would basically corner it into this fence/woodshed area...when the deer would try to leave that spot, my dog would push it back into it...she never did do anything to intentionally harm it. Once I came down to where the deer was, she basically backed off as to say it was my problem now. It was quite bizarre, as I never formally trained her to herd, just the genes in those particular dogs. She did that to a barn cat I had as well, she'd occupy herself with making sure the cat didn't wander too far from the shop.
The whole wild animal thing is kinda outta wack here. There are quite a few people who feed the deer, so the deer have no fear of anything...it seems as if they don't even care about natural predators. Along with the abundance of deer, we also now have an abundance of mountain lions. Now people are bitching about how common lion sightings are and think we should be out hunting lions.
I'm not a lefty greenie type guy by any means, but IMO this is just nature trying to correct an imbalance caused by us. If people would stop providing an unnatural amount of food and water, maybe the deer population would migrate back out into the backcountry...and bring the lions with them? Hunters would actually benefit as well, as the deer would actually be out in the public land.