@ToddL I'll throw another thing out there that a lot of people probably haven't thought of: BOOZE. Doesn't matter if it's the hockey game or a day at the lake, everything revolves around massive alcohol consumption nowadays. America has always loved a cold beer, and there's nothing wrong with that, but it's becoming more and more the sole focus for why a group of people get together and go boating, or do anything for that matter. And they don't drink a six pack, they drink a case. I see it here all the time. Pontoon boats, deck boats, and the sandbar are king, and water skiing is dead.
As for restricted hours for different activities, that's an interesting thought. I don't know how it would work in terms of "slalom only" hours, but I know that the same basic idea is part of what killed the water conditions at my local lake. Let me relay the story: Back in the '70s, a group of bleeding hearts made the lake no wake from 8:00 PM to 10:00 AM. Sunset to sunrise like everyplace else just wasn't good enough. To add insult to injury, towed sports have to end at 7:30 PM. This brought about several problems. First, it eliminated that magical time at dawn or during the last 15 minutes of dusk when the water flattened out perfect and you could really ski like God intended it to be done. Secondly, with fewer hours available, everyone rushes out there right at 10:00 in hopes of getting one good run because the lake just explodes into life within minutes. You have to have the slack out of the rope at 9:58 if you want to get 5 good minutes of slalom in. Once 2 or 3 wakeboard boats take off, it's over. And lastly, it has only fueled the rivalry even more between the fishermen and skiers. The fishermen got their way and got some time set aside for themselves, and that grew into a bias on the part of the law enforcement. If you are skiing at 7:29 PM you get stopped with the lights and siren, but if a fisherman is making a wake at 9:30 AM, the cop is never around. Then that still wasn't enough, so now "for some strange reason" the fishermen hit their electric motors at about 9:50 AM and start spacing themselves equidistantly in the high traffic areas so that it's impossible to follow the traffic pattern without "annoying" them.
The above is why I finally started skiing on the river 10 minutes down the road, which has 18 miles without any no wake zones and you can ski dawn to dusk. Best water conditions this side of Minnesota and the slalom crowd still hangs out there. Don't know why I waited so long.