I've been thinking about it like this:
This impacts people who buy and flip contracts on the new resorts. This now won't be something you can do as easily. I fully, truly believe the first resale contracts for Riviera were a test of this, vs a distressed buyer. Example: giant rental groups. This is not insignificant business, renting points makes money. And the more people that rent, the less rack rate rooms are bought. So if Disney tests out this resale restriction, they force their competitors to change business models. Rental groups either wait for resales and have to manage points that are only valuable at the single resort (possible), or they want the flexibility of using those points at any resorts (for the rental pool value) and buy direct from Disney. If they bought new those organizations would also have to rent at a cost that made sense for them to lose whatever original investment on the resale market or hold onto those points. Again suddenly won't be able to undercut rack rates quite as easily, the appeal of flipping of stripped contracts on the resale market is now reduced, or because a resale contract comes along that is a good beefy buy (loaded contract), flipping out a used contract to replace it with a loaded one is also a bigger business decision. It also forces investment by rental groups back to the new DVC resorts specifically one way or another if they want to be able to rent into that resort. So Disney limits the resale market, eventually driving the money back to DVC.
And for the rest of the regular old buyers - they face similar decisions as above....on a smaller scale, plus no blue card. The resale pitch isn't quite so good either, you can buy resale points but they are ONLY good at that one resort. No availability if you want to take a trip? Tough cookies. Because you'll be competing with any person still holding direct points for any resort, plus your fellow resort specific resale people. Most people buy DVC because they want to go to Disney, and a lot of us can only go during specific times of the year. So if you buy resale and can't be flexible? Good luck with that.
With time and enough stories about above, the debate on direct/resale becomes much more serious. Buying direct becomes much more appealing. I.E - Need an April Vacation week? Better make sure your points aren't locked into one resort.
Already a good number of people will buy direct for some amount just for the blue card perks... as they play with this mentality, that buyers have already shown (buy 75 points direct and then resale, so they know a good chunk of us will) suddenly $X more per point for all the flexibility and perks, starts to become mickey math. AKA: Who cares about that X*$1000 today, if I can take the vacation I want and be in the "cool kids club" for the next 50 years.
Anyhow, to me Disney is playing the long game on shifting the buying pattern for DVC, the rental market competition for cash rooms and controlling the resale market. This will work and they will come out on top as the new resorts are built.