I think it's very easy to use your points elsewhere. I've had no problems getting into the
DisneyLand hotels (including concierge level at the Grand Californian,) the Biltmore in Phoenix, and the Hotel del Coronado in California. Unfortunately, as you've seen from these other posts (and the many others that will probably come) this is most likely because the
DVC points are worth a fair amount of money and it is *rarely* (if ever) a "good deal" to use them anyplace other than the DVC resorts.
However -- it can be done, it is done, and you should certainly include that capability in your calculations when deciding whether or not to buy into DVC. Just don't expect to find anyone who will wholeheartedly endorse the use of DVC points to stay at these other places.
On one hand, paying DVC prices up front to get enough points to be able to stay in the other timeshares on a regular basis seems silly if you can afford a different timeshare that also gets you into these places for less money than DVC. (Or, if putting the amount of money you'd spend on DVC points into an income-generating investment would result in enough money to take a regular trip to these places.) On the other hand, paying DVC prices for more points when you expect to use them on a (semi) regular basis for a "blowout" time at Disney and the other places the rest of the time may, indeed, be a cost-effective way to spend your money.
As always, it's up to you. (Good luck!)