Sorry Sweetheart you are wrong.
When I purchased my mug in 1998, there was no sign, there were no rules, there was no policy. When was the first time, if ever, you visited Wilderness Lodge? Can you show anyone a policy that was posted in 1998?
The point on spending $12 is well taken. In light of the thousands spent on each visit, it is irrelevant. However, the mugs are made of a different plastic than a baby bottle, so that argument does not apply.
However, what you and several other people refuse to recognize is that Disney sold mugs at certain resorts in the '90's with a "refill for life" feature. Disney has since changed to selling mugs that have refills for length of stay. Those are different mugs of a different design, and I acknowledge the new policy and said mugs limited "life".
When WDW first opened, Florida residents were offered lifetime passes. Using your logic, Disney has every right now to revoke those passes or place limitations on them. No they can't and of course, never would. By selling the passes, they made a contract with the owners. The same, although to an incredibly less extent, holds true for the mugs sold with "free refill for life" privileges.
Like I posted previously, I don't reuse the length-of-stay mugs I purchased from Beach Club and Boardwalk. I barely use the one from Wilderness Lodge. That doesn't mean I don't have the right to use it. If I do, I don't think I am doing anything wrong.
The mugs that have been sold for the past few years are sold under the condition that they can only be refilled for the length of your stay. Nothing of that sort existed in 1998.