The problem isn't quickscoping itself. The problem is the map design of every single map.
In MW2 my favorite weapon was the SPAS12, and I use shotguns in every game, so small maps work for me in general. However, in WaW and MW2 I used all kinds of guns because the maps were varied, and in some maps you hade wide open zones where you could snipe at least 120 degrees in front of you. In BO1 the width of sniping fields shrunk, in MW3 it was gone- MW3 was the worst game for sniping unless you liked camping corridors. Sniping should be about finding the high ground and picking off enemies, but there is almost no high ground anymore.
Now, I assume people don't like being sniped across the map, but that is the most fun kind of sniping there is, and when the field is wide open and you can shoot anywhere on the map, then you have to scope in more and search all over, instead of aiming at a 15 degree range at the end of a hallway and just pull the trigger if someone turns that corner.
BO2 maps are slightly better than MW3, but not as good as they used to be for sniping. If you make 'real" sniping impossible by virtue of map design and leave sniper rifles in the game, all that is left is quick scoping. I barely touched snipers in MW3, then went back to the older games and realized how much I used to snipe.
If the maps become wide open again, where I can find multiple places on each map and shoot you from almost anywhere, then quickscoping will become the rare annoyance it used to be. I love "real" (game) sniping- bolt action from 150-200 yards away- but the maps after MW2 don't let me do it.
So, people who hate being sniped, which is worse? Being quick scoped or being killed from across the map? Personally, I prefer the across the map, both giving and receiving. Getting shot from that distance, I respect the shooter,and making the shot is much more fun than going for what is essentially a lucky trick shot.
I don't care if people quickscope, I just think using the weapon as intended is more fun.