If you are really interested in owning a timeshare to do non-Disney things aren't some of the other timeshares out there a better option in regards to purchase cost, MF and trading? How would Disney be able to compete with them?
Yes there definitely are, but there are two perspectives to consider.
From the
knowledgeable timeshare user perspective, you can buy some VERY good timeshare products through eBay and other sources literally for a few hundred dollars including all closing and transfer costs.
A couple of years ago we bought the rough equivalent of 600-700 DVC points in Wyndham via eBay for less than $2,000 including all costs. The MFs are substantially less than DVC, we have access to almost 90 resorts nationwide, and FULL individual RCI membership included in our MFs.
Marriott, Hilton, Bluegreen, Starwood (Sheraton, et al) and several others offer similar options, but I don't know much about those systems.
Even if you buy from the
developer 
scared1

at a comparable price to DVC direct, for
non-Disney vacations there are a number of better choices than DVC.
*****
But the
perspective that matters to Disney is that
of the timeshare developer. For a particular destination, what are the building costs, and can they sell that resort at an acceptable profit level? That's really all that matters to the developer, because they are finished when the last contract is sold.
My opinion is that Disney should focus where they have a unique advantage -- and that is primarily onsite at WDW.