It's actually a good point though... why, when people find a new, odd creature do they only think of killing it? That Japanese shark thing is only one example.
That shark wasn't an intentional kill though, they attempted to relocate the creature away from its natural habitat (for further examination and to probably preserve the species) and consequently killed it inadvertently.
But in general, a lot of folks are typically afraid of what they do not understand and a first reaction is to act violently to it "OMG!! WTF IS THAT THING!? KILL IT!". Unfortunately.