I have come to believe that the old saying aim small to hit small is a truism. My two RUMs are equipped with 4.5X to 30X Bushnells. You can jump shoot OK on 4.5X and see bullet holes in white paper at 600 yards on 30X. Plus they double as a spotting scope.
I agree that the larger magnification scopes have an advantage with the 'aim small miss small' train of thought and also double as spotting scopes when you're getting set up on an animal. Even after the shot it's nice to be able to see more detail... from the impact to any clue of what's going on down range could help in tracking and locating, details that you might miss with a lower power scope. You can always turn them down if you don't want it. I've never had a 30x scope, but something around 20x is ideal for me.
Obviously need to have high quality optics for a clear image. What always amazes me is when I shoot my Vortex PST 4x16 at the range right next to my ATACR 5x25 and how superior the ATACR image is over the PST. I can spot bullet holes in paper out to 500 with the ATACR while I can't see them with the PST past 200.
With that said, when I'm only using the 4x16 PST and nothing else to compare it to, my eyes don't think it's all that bad, and I shot my biggest bull at 630 yards with the PST...
So when are optics good enough ??