I work as a ski instructor in the Alps and have already had experience with this. Say what you want, but this system, if used in clearly distinguished "ski school areas" only, helps us a lot. It's not that much about the kids - it's about our responsibility if we have 6 or 8 kids and can't possibly watch all of them during the lift ride. Most ski resorts build 8 seaters nowadays and even if you sit in the middle, you can't control all of them. It's a shame that some(!) kids have become so dependent (or hyperactive, or unable to follow instructions) that you can't leave them in a chair lift on their own any more. However, it is not our job to change that.
This system is about protecting ski instructors from legal claims. And not only ski instructors - lift operators, too! Because parents of kids who've hurt themselves tend to look for someone to blame. Especially US Americans should know what I'm talking about. Remember the McDonald's coffee case?