Why shoot a presently perfectly healthy deer only because he has a wound? I must be missing something?!?

From Mausers pic, I can see that arrow possibly going high just over the spine...its hard to tell. I didnt see it in person, and would have passed if I did with that deer's body status.

Just because one is down, doesnt mean you should automatically count him out....taking the buck is fine, but using the injury as the reason, seems silly to me. Sure if one is direly sick with blue tung or something and it has no chance of making it, I'd end the suffering too....but these are pretty resiliant animals, a broken leg or flesh wound doesn't mean they are crippled and suffering for life...they can survive just the same as other deer.