Where I see an ethical issue in long range hunting is in fair chase. As you well know, an animal like a deer has its senses and capabilities as defense mechanisms.
There's a point in there where the animal loses all chance of detecting a hunter, and if it's simply because of technology, I see a problem. Fair chase hunting is about using one's skills at stealth and concealment to avoid detection and then be able to make the kill. For that the game has to have a chance to see you, smell you, hear you, etc.
It's a gray area, for sure. I wear camo and shoot a modern bolt action.
I'd rather see hunters try this as an alternative: See how close you can get to a deer. Can you stalk to within bow range? That's far more impressive than a long shot to me, because I know how easy it is to spook a deer when hunting.