We had reserved a studio for one night at the Hilton Head Island resort and were upgraded to a 2 bedroom. No explanation was given to us.
Hilton Head is the one main exception. Many of the 2-b/r villas there are dedicated ones. There are not that many lock-off's, or studios.
During slower times of the year HH does not run anywhere near capacity. To help defray costs they try to let rooms go for cash. Since most people, who are not members, want the 'cheapest' room, they want the Studio. They don't want to pay for a 2-B/R.
So, if a member has reserved a Studio, and
DVC is able to rent that Studio for cash, AND there is a 2-b/r villa that is going to go unused, DVC has in the past upgraded the DVC-member from the Studio to the 2-B/R villa, and then let the Studio go for a cash reservation. This brings in a little money. The alternatives would be to have the member keep the Studio and let the cash member have the 2-B/R unit (at the price of a Studio). Bad Idea!!! Or to have the member keep the Studio and let the 2-B/R villa go empty, and the cash person not getting a room at all.
Upgrading the member and letting the Studio go for cash is a win/win.
It's happened to us also, and it's great when it does happen.