My history is not as long as most, but in my case if I ever encountered any issues... they were minor in comparison to the fun I had. So no issues here on my end. I know there will always be someone that is drunk.. as that is just unavoidable... as it is any time you go out anywhere on land or sea.
As someone mentioned above regarding locations where you are sardines... combine that with overindulging on alcohol and its inevitable. I don't think there is a real solution other than to go to a less fun cruise line for folks that are upset about it. For me.. I kind of like being around young people having fun... makes me feel less old.