I understand why people want their bikes to run lower RPMs on the highway....noise and vibration would be the two big factors. IMO high frequency vibrations will fatigue the rider faster than low. I think the other misconception is they feel the bike is underpowered or geared wrong when the RPMs run high.
It all depneds on what the bike was desinged for and the engines size. My little 4 banger Ford runs at 3100 RPMs at 75 MPH....my big Dodge pickup with a V8 runs the same speed at 2200Rpms....I don't fault the Ford for that...its got half the engine but also gets 3 to 4 times the MPGs....
Ride more, worry less....
"Beer cans explode with a nice loud pop when they are hit by a Heidenau K60 at 40 miles an hour. Now my bike smells like last call..." Me