It likely depends upon the season/timing of the set reservation. Most renters don't plan their trips as far in advance as we DVCers do.
Also, set reservations can not be offered on our Rent/Trade board farther out than 30 days prior to check-in date.
Given the current state of the economy, there are also likely fewer renters in the market. I know some friends of mine just had a baby, she lost her job, as the company she worked did stained glass restorations, and a lot of churches aren't spending $$ on that right now. His job is in retail, and has cancelled all management performance bonuses, which made up a good sized portion of their income. They've had to move back in with his Mom...and won't be traveling to Disney anytime soon, even though I provide them the villa at no charge.