Here is how I see it - stretching your hunting distance 3,4,5 times of the acceptable average serves only one purpose: purely egoistic bragging rights - be it to yourself, family, friends, internet. Since the decision is egoistic it is unethical by definition.
You're being a bit judgmental aren't you. Pray tell, where did you learn what the "acceptable average" is and how do you know that those who shoot at ranges you believe are beyond the "acceptable average" are doing so for "purely egoistic bragging rights"?
Perhaps you've heard the term "fair chase"? It means the animal has a chance to get away in case you don't know. It would seem to me that attempting to take an animal at 500 yards where it had an extra half second to get away would be in the spirit of fair chase.
If you really want to be "ethical" and guarantee a clean kill EVERY time, you probably better tighten up the range and make sure the animal is in a pen. Oh, but I guess that's how the meat gets on the supermarket shelf.