IMO, the cause and effect is backwards here. If you look at the very comprehensive ROFR thread maintained on the DVC boards, you will see that prices started dropping steeply about the time the recession hit full force, and ROFR did not really slow down for almost another year.
No---the ROFR process doesn't even start until you have a willing buyer under contract. Once the contract is executed, it is sent to Disney, which has a month to decide whether or not they will buy it under exactly the same terms. If they do, Disney pays the seller and gets the deed. If they don't, the contracted buyer pays the seller and gets the deed. But, there always has to be a willing buyer first, and once there is, the seller will be paid. The only question is who does the paying.
That's why ROFR turns out not to have a huge effect on the resale market---the market is still set by willing sellers and buyers coming to terms on a sale. A few of those have some insight as to what DVC is doing with ROFR, and try to price accordingly, but they are generally swamped by larger forces. For example, during the height of the recession, there were quite a few owners who had to sell no matter what price they got---they were trying to liquidate whatever they could. There just weren't enough buyers to keep up, and that's what led to the drop in prices. The volume *also* spiked, and my guess is that's what led to the curtailment of DVC exercising ROFR. They do not have infinite capital, nor an infinite number of buyers touring the DVC properties, *plus* they had their own shiny new resorts that also had to be sold.
They may start exercising more frequently in the future (it has picked up slightly already) but I don't know that I would count on it in my buy/don't buy decision.