Here's my crazy idea. When someone checks out of a studio, the glasses are removed. Even the standalone DVC properties have restaurants or quick service counters, which means...they'll have dishwashers! Remove the glasses from the room, have them washed in the resturants/QS' kitchen..., buy some extra glasses and rotate them so Mousekeeping doesn't have to make two trips to get them washed and return them to the rooms. I'll be happy to donate an extra dollar-fifty to a buy-extra-glasses fund.
Crazy idea #2: Even when it comes to the ginormous DVC properties where it takes you a half hour to get to the food court, people still buy refillable mugs. DVC could make some commemorative-but-SMALLER DVC-themed glasses (6-8 oz), that could be purchased right when you check in as a special keepsake or premium. Make them ONLY available to DVC guests, and at a reasonable price (heck they can be taken out of dues, and the price charged can go back into the dues, there's no doubt that they'll sell). Make them glass, NOT plastic, so people won't want to bring them outside of the rooms (and if there isn't already this rule, maybe institute one that states, for insurance reasons, glasses and other breakable, shatter-able containers are not to be used around by the pools or playgrounds, food courts...anywhere but in the individual rooms. DVC guests not only now have glasses, they have another keepsake/memento of their trip, but since they can break if dropped, theyr'e forbidden to bring them outside the rooms (but they can bring 'em home), which means they shouldn't/probably wouldn't cut in to the lucrative refillable mug racket, especially if they were ONLY made available to people staying in DVC rooms. Even people staying at Boardwalk, AKL, Beach Club or Wilderness can't buy them unless they're staying in a villa. To cut down on gawkers saying "What are those glasses, how come they got 'em, *I* want 'em!!!" the DVC guest is told on check-in, how much the glasses are, what the rules are for using them, etc. If the guest wants them, they're either handed over in a generic brown box with no fancy packaging, OR they're ordered at the desk and delivered to the room shortly thereafter.
If people don't want to purchase them as soveneirs, plain glasses can still be delivered as requested, though of course left in the room at checkout.
I dunno, makes sense to me.