You read my mind! I was just about to say the same thing. Or, they could go back to the original mug plan, which is very green, where you purchase a mug, its good forever. Since they continue to raise resort prices anyway, the resort price would cover the cost of the drinks, but the guests would believe they are getting something for free. Disney would actually make more money while looking very generous, strategic marketing.
Personally, it doesn't really effect our family. When you stay in a moderate or higher you get free coffee anyway. We don't drink soda, and tea bags are easy to bring. With the DDP I never need additonal drinks, but if I did need more I could use the snack option. And since the water in FL tastes nasty, we brink flavor packets anyway.
Now, if they sold a refillable mug for alcohol...... >;-)