That's largely because wages took a big jump this year.
The key thing about Dues is that they are legally required to recover the actual costs of operating the resort. When the actual costs don't change much, dues don't change much. When the actual costs change a lot, dues change a lot. And those costs tend to be dominated by what Disney is paying their Cast. Looking at, say, the OKW budget, Housekeeping is the #1 cost, followed by Transportation, then the Front Desk. Some of those costs are materials (cleaning supplies, fuel) or maintenance (keeping the buses running), but most of it is paying the people who do those jobs. Last year, Disney had to up their pay rates to be able to staff the resorts, and those costs are passed along to the owners.
There are other components that matter: Maintenance costs may go up as a property ages. Utility prices can be volatile. But, the basic idea is that Dues grow with the costs of paying the staff.
That's very different than the price of direct points, or the rate at which Disney rents hotel rooms. Those are things Disney gets to choose, and are going to be much more driven by how much demand there is on the part of customers to stay at Disney resorts--either "in bulk" as DVC Members, or a la carte by just renting rooms as they go.