Think outside the box for a minute. This is not a standard "hotel", this is a resort.....
The problem is not they are getting paid for the room, but people are not paying for meals, buying merchandise, buying tickets, etc. People are booking two rooms for one night and only spending the money on-site they would do if another family was in that room.
Disney is a business that has stockholders that need to see the bottom line. If everyone did what you say, they would money...is it fair to you, maybe not. But it is Disney's rules and we need to abide by it.
Exactly, as a business are they really going to turn down money "just in case" a "better" trip gets booked instead? With that logic, why allow anyone to book one night at all? Why wouldn't they have a minimum three night stay? Why allow anyone to book without a ticket package? Or a dining plan? What if all someone wants to do is spend a week at the hotel and drive off property to eat meals? Not likely, but how would they know what the intentions are of someone who doesn't buy their tickets with their room?
How is the money Disney is making any different with OP booking this room then say a local with an AP that wants to just spend one night and brings a cooler of food from home, therefore, won't be spending any money on restaurants during their stay. All they want to do is hit up their favorite rides for the day. How can they know that that scenario isn't going to happen? And if they did know, would they refuse them?
Disney of course cares about the bottom line, but they are also all about customer service and refusing to allow a guest to PAY for a room just in case a better deal comes along is NOT good customer service. In fact, I could actually see if going so far as discrimination. That's like saying if you don't make at least $X amount a year, you can't stay here because you don't have enough disposable income to buy a lot of souvenirs. They would never say that (can't legally) so how is this any different?
I guess I could MAYBE understand if it were during a super busy time, like New Years Eve or the 4th of July or something where they are pretty much guaranteed to fill every hotel, but for some random other night, I really don't see the logic. Like I said, I don't know Disney's current policy on this, but it does not make good business sense even if it is a "resort" and not a regular hotel to turn down guaranteed money for a "maybe" future reservation.
Come to think of it, just last year when we went to WDW, we couldn't decide on which hotel we wanted to stay at, so I actually had two reservations booked, one in my name and one in DH's, for the same time period just at different hotels. They never said a word. I of course cancelled the one I didn't want long before the 45 day window, but they had no problem allowing me to book it. I didn't mention the first reservation while booking the second, but I assume their systems could tell.
OP, I would do as others suggested and either book through a TA, Travelocity or Orbitz, or just try doing it yourself online. Once you've paid the money, they aren't going to turn you away when you try to check in.
for a fraction of the price
. Can make the one night memorable 
.
