High operational costs? You lose all credibility in response when you make a comment that directly contradicts the reality. Waterparks do not have high operating costs, especially when compared to a theme park.
Well I didn't compare them to a theme park because... Disney doesn't have a theme park to operate in its place. Nor is it directly competing with that as a reason to exist. What it's compared to is more what Disney has for everything else on the property... aka entertainment it has in recent decades convinced OTHER companies to operate and pay Disney for the privilege to be there.
They are high cost to operate. High maintenance, include large amounts of labor, including labor that costs more, with limited operating hours compared to alternatives. There are reasons you see most regional waterparks die with only the largest, strongest, usually diversified companies lasting 10+ years. They also have high overheads like insurance and attraction refresh investments necessary.
Contrast this with something like Golf, retail, bars, etc and you can see how Disney has to spend a good bit of money all the time to keep these businesses running. Verse alternatives like... sitting back and collecting leases and profit sharing.
Add into this, this is a business Disney largely "gives away" in its ticketing strategy, further reducing its ability to directly control its own PnL... due to a large part of their admissions coming from whatever their split is from their combined ticket revenue model.
Furthermore, Disney has largely not made significant investments in any of their waterparks after the initial opening. How can you say "I wouldn't be surprised if Disney actually shrinks it's water park investment in the future..." when they've never really made consistent cap-ex improvements in the past? Blizzard Beach is the same park as when it opened. Typhoon Lagoon has had one significant addition, but clearly on a budget and a more recent addition that replaced a retired attraction.
How can I say? Well I'm not one that said Disney hasn't made significant investments - because I know they've had to to keep is running as they have. You don't get a water park to run and stay in great shape like they have for 30 years without spending a hefty amount of money.
They've made attraction additions at TL (the water coaster, the new family raft ride, and I believe at least one other set of slides was changed) - but yes, not at the pace common at other parks. Largely because most regional parks add rides to try to bring people BACK to the park - Typhoon Lagoon doesn't have that same need when it's largest customer base is the WDW audience already there. Plus, when they needed more capacity, they instead just added a whole other park!
Complaints the parks are largely stagnant over the last 20 years are valid - but Disney has already shown through its history that this doesn't seem to be the deciding factor. My argument is the bigger factor is the larger macro economic approach Disney has been taking towards WDW.
The Disney waterparks for the most part do not extend hotel stays. Most folks visit Disney for the theme parks and the waterparks are an alternate activity
Uhh.. that's what 'extend stays' means. If there is nothing else to do, you don't plan as long of trips. When Disney pumps the marketing engine to tell everyone about 'all the amazing things to see and do at WDW!!' - people plan to make time to try to experience more... aka... extend trips.