IMO the biggest issue Disney did to themselves is push people to plan out a lot of their days when at Disney World.
It makes sense thought for Disney (especially Disney over other parks) to make people have the ability to plan out there days. First Disney has multiple parks, multiple different operations points. By having plans be done in advance, you help allocate manpower and help with crowd control/dispersal. Genie and park reservations are an extension of that over FP. Hell the 180 dining reservation was almost a defacto park reservation system. Yes park hoping would skew those numbers slightly but it would give you a trend.
Second while i have never been to Cedar Point Ohio, it doesn't strike me that that park, or say six flags, or even Dollyworld, has the local competition that WDW has. If your booking a trip to Cedar Point, you are likely going to the park, or I guess hanging out at the hotel? If there was no planning with WDW and you could really just go day by day, you would allow people to say, hey maybe instead of HS today, lets go to universal, or bush gardens, or Sea World, or ..insert other Orlando/FLA based activity here. Pre-planning of your week long trip locks you into WDW. Sure there is going to be some flexibility, maybe i skip a dining reservation bc i got a FP (now LL) that i wanted day off. But your not leaving your pre-planned park.
And third, this is a little subjective, but I always found pre-planning meant i was trying to fill the day, fit as many things (and spending opportunities) as possible. Look there is a dining reservation we can get for lunch $, and we have fast passes for slinky dog dash 2 hours later. Nice, we can fit in building a droid in between, or look we can get into Olga's after, ect. Now lets make sure we purchase the LL for Rise at the time we want $ so it doesn't interfere with our droid building $ or hitting Mama Melrose for Dinner $.