Said it before, and I'll say it again, there's no technological reason they can't build an
ala carte custom
DDP system that allows you to purchase the number and types of credits you want/need that would be valid for the duration of your resort stay.
Credits could be purchased individually and/or in discounted "packages" under such a scheme (e.g., choose a package like the current basic DDP at a discounted rate per credit and add
N number of extra CS credits at the "rack" rate).