Robin - maybe they don't seem to affect me as much because in all the theme parks around here (and the zoo) they rent only wagons, not strollers. So imagine all the strollers at WDW replaced by wagons (huge ones, not little radio flyer ones) and suddenly the backpack issue seems insignificant. Add parents who let their 3 year olds push the wagons around (no not pull, that would be too easy) in circles in the main areas of the park. So I guess it is part of my "theme park" frame of mind. I don't think I'd ever realized WDW didn't allow them. We've always flown, so bringing a wagon never would have even crossed my mind, but didn't know they weren't allowed!
I agree Goofy, that it's people that cause the problems, those not paying attention with or without backpacks. Those who think they can walk ten abreast slowly. Those who stop in a huge group in the middle of a small pathway. One of my most annoying (fortunately not at Disney anymore thank goodness) is people who walk while swinging a lit cigarette right at the level of a child's face. To me, this was always the biggest danger of allowing smoking anywhere, especially in lines (where even in parks around us it isn't allowed, but frequently not enforced). If at Disney, someone is standing off to the side somewhere smoking (not in a "smoking area"), it wouldn't bother me. But doing it in a crowded area, especially full of kids - come on! Not trying to get this thread off on a tangent, but point out that there are other, annoying habits of people as well!