As other have intimated, I’m wondering if the whole goal this (outside the ultimate goal of making more money) is to decrease length of stay, but compressing the same spending into fewer days. If my family plans a visit for 6 days, but with this new FP system, we can purchase Lightning Passes each day, we can cut our trip down to only 4 days. I’ve essentially transferred my two extra days’ expenditures into Lightning Pass expenditures.
I have no doubt Disney has dissected the data every way possible. Maybe they’ve determined they can increase daily per guest spending by compressing trips and squeezing more people (at a higher per day spending rate) into the same space as before.