Yes, to me, the conversion of hundreds of deluxe hotel rooms to DVC villas suggests that they believe a ceiling has been reached. It reminds me of the quote, in order to achieve our goals we must lower our standards. Instead of developing an aggressive market strategy to fill unoccupied rooms, they will remove hundreds of rooms from the inventory and artificially inflate the occupancy rate.
Disney has realized that, going forward, they will no longer be able to fill the number of deluxe resort rooms they once did. While I am hardly the first person to say this, one really has to wonder how the TDO execs must have so little confidence in their own (resort) product. If the suits were really as dumb as they seem sometimes, they wouldn't be able to start their own car to drive home at night. Hence, they can see the writing on the wall as well as we can, and even though they may only be interested in propping up the financial numbers for another few years, they appear to be completely unable (or unwilling) to take corrective action.
The solutions aren't exactly rocket science, nor do they necessarily (or immediately) require significant capital investment. Indeed, there are several posters on this board with workable suggestions (more FP's, complimentary recreation activities, better transportation, etc.) to improve deluxe resort occupancy. What is required is providing the guest better value for the price paid; Disney can even "get away" with some degree of inflated prices because, well, it's Disney and the nostalgia/"brand loyalty" effect hasn't yet entirely evaporated.
However, rather than taking steps to increase demand, Disney "solves" the problem by reducing supply. That's backwards, but it's even worse than that, because substituting DVC for standard guest rooms will exacerbate the occupancy problem. Many DVC members are the guests who formerly stayed in those same deluxe resorts, so while DVC has been adding room inventory, it has come partially at the expense of deluxe (and moderate, at least) resort demand. Further, guests renting points from DVC members continues to grow in popularity; This (drastically) undercuts Disney prices and, again, is one less family who likely otherwise may have reserved a deluxe or moderate resort room. While it works against our interests as Disney consumers, I am surprised Disney does not explore ways to curb (or dissuade) point rental to just anyone, because the 'problem' (from their perspective) is only going to get worse.
I've said this before in the context of DVC discussions, but I think there is something else going on as well---a reduction in exposure to risk. 9/11 scared the living daylights out of TDO, and with good reason. The falloff of travel demand---particularly by air---hammered WDW hard. They closed entire resorts, and were giving away buy-four-get-three deals just to get people to show up. WDW is deeply exposed to changes in the air travel market. There was an interesting Yee piece many years ago on what happens to WDW under an oil price spike, and it's ugly.
And, if you look back, that moment of 9/11 was the turning point in how TDA viewed hotels vs. timeshare---that's when they went all-in on DVC. They haven't opened a single new hotel room that wasn't already under construction (in some form) before 9/11 happened. But they have been converting hotel rooms to DVC units. This makes sense because it shifts some risk from WDW to DVC owners---the owners get a break on total lodging costs in return for a commitment to occupy (or, at least pay for the operation and upkeep of) that unit for many decades. If the owner decides that travel to Florida on an annual or semi-annual basis is no longer interesting, it is their problem to unload the contract, not Disney's. So if the travel landscape changes, Disney is not left entirely alone holding the bag
While you are quite correct that 2001 was a turning point, the downturn initially occurred earlier in the year, prior to the September 2001 terrorist attacks. Obviously, the situation worsened after that (though the parks were hardly deserted later in the year), but the point is Walt Disney World was simply overbuilt with resort rooms at all levels. There simply wasn't enough demand for the existing room inventory - even without consideration of risk in any potential economic downturn - with the new abundance of value resorts drawing many guests who formally stayed at moderate or deluxe properties. That problem sound familiar?