And even the ones that don't bite or attack people can be problematic. They can carry and spread disease, including some nasty stuff...
We can get STDs from them.

In fact, that's where HIV originated: from human exposure to an infected chimp.
Like I said, I don't like to kill things, but sometimes that's really the only option.
Same here. I'd prefer to not have to ever kill anything at all. I'd like to live in a world where all the critters get along with humans in perfect harmony. But we live in a Nietzschean/Darwinian world, not the Garden of Eden, and that means we must actively manage the environment if we want to remain a part of it at all.
Speaking of actively managing the environment, I'm still hoping to be able to plant some blight-resistant American Chestnut trees at some point. That's the one genetic engineering project that I really want to succeed. The world doesn't need the Dodo or Direwolf (

) but resurrecting the fabled Chestnut forests of Appalachia would be absolutely wonderful. It could potentially revolutionize the environment and the economy of the whole region.
I'd like to see woolly mammoths, too, though I doubt they would choose to live this far south.