I agree propensity to exchange will be low. And while other locations in aggregate will be more popular I suspect that if it was available Orlando would be the #1 getaway destination for DVC members. The vast majority go there very regularly, so an inexpensive add on would be attractive to some. And the vast majority of the "top tier" getaways are in Orlando. DVCers would probably prefer getaways at the Marriott on Maui vs Marriott in Orlando, but that isn't available.
If even 5% of DVCers booked an Orlando getaway every second year that would be over 10,000 Orlando getaways per year, which would absolutely dent inventory.
Anyway, I don't think its a big deal because I doubt DVC wants its members getting super cheap deals elsewhere in Orlando, so they will almost certainly be blocked. But if not I think it would make a big difference to availability.