RE: Simplicity?
I doubt modern bows allow a knowledgable archer to hit his target any more accurately. People have shot incredibly well with just about every type of bow for many decades. The advantages I've noticed have been more easily seen when looking at the average hunter. The biggest difference I've noticed comes in the area of manufacturing tolerances. I think limbs are better "matched", limb pocket tolerances are tighter, cam alignment is not as variable and string creep is more easily controlled. When you hand a bow to the average bowhunter that has these advantages, he shoots better for a longer time. Most bowhunters wouldn't recognize poor cam alignment and could be "hit in the face" by a sloppy limb pocket and would never know what hit 'em. I think it's easier to take almost any bow off the shelf and shoot well with it, even the real low-end models. The average bowhunter of yesteryear was incapable of timing or tuning a twin cam. They didn't recognize string stretch/creep and if they did, they didn't know what to do about it .
Shooting the very best always has required expert knowledge and still does. However, I truely believe an average hunter has a better chance of shooting consistantly well today, than he did 10 years ago.