Late to this thread I posted, but I do have to give an update.
People do not randomly shoot animals in National Parks. In normal situations, firearms would only be used to defend one from an attack. Millions of people travel through these parks annually and the incidents of attack are very rare, but they do happen. Mostly caused by dumb arse humans encroaching into the animals safe space.
There are exceptions though where defending oneself from a predator may become necessary. Although those parks are built to preserve and protect those animals, humans do need to monitor and control the populations so they don't overpopulate, become diseased and spread that disease amongst the overall herd.
On occasion as biologist monitor the wildlife, hunters are allowed in to harvest enough animals to keep the food sources inline with the animals that feed from them. If food sources are over sourced, the herd overall suffers.
That happens nation wide for the most part. The elk hunt at the Wichita Mountains National Refuge is an example.
I take no issue with people being armed to protect themselves from 2 or 4 legged creatures should it be necessary.