I agree, unless there was some sort of a problem with the rooms in the WL side, there's no way you'll get a free upgrade to a villa. Those villas are not owned by WDW, but by DVC members, and it's the members dues that pay for the upkeep of them, so giving them as free upgrades would actually be technnically illegal I think.
If WL needs to use them because they don't have regular rooms available during some sort of emergency, they still have to pay DVC for the use of them, which isn't cheap and affects the bottom line of that resort. Each resort is accountable for their own bottom line and cost center, so they'd be foolish to be giving upgrades that actually cost them money.
Anne