My opinion has been that those guys took different shots than we do for several reasons.
1. They had fewer shots than we do, due to game management being much more refined in our time. Simply stated, many of us have more animals to shoot at because game populations are better now. I'd bet that people's definition of an ethical shot in high game density areas is more conservative than the opinion of those people who live in low density areas and get relatively few shots.
2. Back in the old days, Fred Bear and Howard Hill lived in a society that was much more comfortable with the killing of animals. Let's face it, many of us have been impacted by our bleeding-heart culture, whether we like it or not. While I do not advocate the senseless wounding of animals, I am conscious of the fact that an animal may end up wounded, by one of my arrows, and I may not recover it. That animal will be eaten by a predator or scavenger, and I can accept that. (Now, I try to take careful shots, and have only wounded one or two deer in my 10 years of hunting them.) I do not worship those animals, I recognize that they are not spiritual creatures nor equal to human beings, and if they get wounded I can live with that. I think hunters from older generations felt somewhat the same way... and more so.
3. We have refined hunting to a great degree. Bowhunters take an incredible number of deer nowadays, compared to bowhunters of past generations. This is due to a greater understanding of the animal, technological advancements, and being able to hunt from tree stands. Hunters in past generations simply did not have the luxury of waiting for the perfect shot like many of us do.
Again, I'm not an advocate of flinging arrows at anything that moves, be it near or far. But I will never forget when I first got into traditional archery, when an older generation bowhunter with hundreds of kills under his belt advised me, "Learn to shoot that bow well. Lots of guys can't shoot anything that that's further than 20 yards away, and frankly, that's embarrassing." I can't shoot much further than that myself, but I've never forgotten those words. I think there was a pride in being able to make those long shots in the older days, that we don't really value now.