The more I think about the restrictions, the more I think it doesn't matter much to Disney - at least not yet. This has probably all been said before by others so thanks in advance for indulging.
The restrictions as they exist provide a much clearer decision between the resale product and the direct product and helps justify why Disney charges any amount of a premium over resale. Unless direct sales very definitively crater, Disney has no incentive to keep the resale price high. In fact it helps them out with ROFR once the resort does sell out because they can buy low, magically add their "benefits" back to those points, and sell them a second time at a much larger margin than with the prior 14 resorts. It also helps direct sales reps be able to more concretely/authoritatively demean or dismiss the option of resale at all to any prospects who ask about it. Others have pointed out that breakage could be an issue for resale owners as well if they have to cancel outside the banking window. That heightened risk, too, is a feature for Disney to discourage people from going with resale (and also a win for Disney overall because points unused are more profitable points, presumably).
This may cause residual higher resale demand for the legacy 14 resorts, but as the first of those start to expire in just 20-something years (which isn't an absurd amount of time) the resale proposition of *those* resorts goes down as well as less resorts are available to trade into other than your home resort.
The only way the restrictions policy doesn't work out for Disney overall is if most DVC direct purchasers are already aware of the option to sell later and proactively factor that in to their decision to purchase DVC, causing them not to buy the new resorts at all. A slight/non-overwhelming slowdown in Riviera sales may not matter much if cash demand for the resort stays high over time s/t they can keep occupancy up overall.
Imagine a world where every DVC resort's rules were like Riviera's. You buy direct if you want to stay at any/every property, if you want to maintain maximum flexibility in vacation planning, you find value in the other membership perks (whatever they may be), and you want the status of a luxury purchase. You buy resale if you can be disciplined enough (and maybe lucky enough) to commit to your vacation plans a year ahead of time, absolutely love staying at a single resort, and can make the financial numbers work where you're likely in the medium or long term to be coming out ahead financially instead of paying cash. They become two very differentiated products - the resale product that most folks on this board know and many of us have convinced ourselves has value has a remaining lifespan of < 20 years, it seems.
(caveat that all this pseduo-intellectual analysis may have major flaws, but it feels truthy to me)