I agree

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I think it could behoove Disney to have some sort of "Genie Dollars" that could be purchased ahead of time and "loaded" onto your
MDE account to be used for LPs as you see fit throughout your trip. Since it sounds like LPs (and other items) will cost different amounts, they can market this as a way to add "flexibility" to your trip -- "spend them your way!" etc.
For that matter, the availability of "Genie Dollars" could be a great way to upsell other products. You might see something like "Upgrade today to a Moderate resort, and get $100 Genie Dollars to use however you want to!" Or "Book today and get $100 free Genie Dollars!"
The benefit for Disney is that this could be a way for guests to feel like they are getting a great deal. (When really, they are only getting something that was previously free.) And once folks get a taste of skipping a few lines, there is a greater chance they will be willing to pay to skip a few more.
I have no knowledge that anything like this is in the works. I'm just thinking through how Disney could make the new system enticing to more people.