How are they missing the boat?
You've just describe exactly how they can spend as little as possible while making as much as possible as long as they can keep an acceptable number of people walking through the gates.
The more crowded and unpleasant they can make it feel, the more money they'll make as long as people en masse don't become wise to the trick and continue to excuse management by suggesting it's out of Disney's control and it's just super high demand for what they're offering because... that's how awesome the magic is?
And as a bonus, they've discovered that part of how they can make it feel that way is by cutting back on operations and staffing to make lower attendance days in the parks feel like busy days, too, allowing them to cut back costs even more while maximizing guest spending.
One would like to think this ability to make money on individual attractions would spur them to start building amazing new stuff to monetize but think about it - why build a new $200-$500 million attraction they'll need to staff and mantain so when it finally opens, they might be able to get $20 a head for people to ride it when they can just up Genie+ by another $5 per person today and the greatest expense is having someone go in change a field in a database?
I'm sure in the half-decade+ it would take them to build that amazing new thing, Genie+ will have risen in price by more than the $20 a head they might have gotten with the attraction, anyway.*
*Of course, they'll still build stuff or gut and refurb existing stuff. There is no way around doing some of that in a competitive market but they're very well incentivized to do the absolute bare minim possible unless an outside force makes them do otherwise, from here on out. They can talk all they want about wanting to make people happy or about trying to improve the guest experience but that's not going to be how they try to make money anymore.
