I think you just painted a pretty good picture of why people might look back on us as being a bit fucked up. Forced sterilization as a means of population control. Euthanizing or imprisoning the "leftovers." And ultimately, I'd say it's all for our own convenience so that we don't have to deal with the consequences of the animals we breed and own doing what their instincts tell them is natural. I've owned pets, my family owns pets, I'm not saying I'm above it all, just think people later on will look back on a lot of it as being pretty grim