Maybe they're too nice looking and people are at first using them for other things? I've used them to hold my stash of reusable bags. Also have used them to stockpile the disposable bags that we use as small trash can liners - at first we would go through them quite quickly but less so now that there's the spectre of the era of free disposable shopping bags might be over we've been using the "liner" several times before dumping them. Other times we've used them as delivery bags for Christmas presents.
All this to say that sometimes it takes a while for the bags to work through the higher order uses. Even then, I agree that it might be rare for a Disney Store bag to end up back at the Disney Store. I mean, does anyone think that anyone will carry a variety of reusable shopping bags so that they can reuse the one that matches the store that they happen to buy something from? That said, I do try to match the reusable grocery bag with the grocery store I'm shopping from.
Also, I wouldn't be harsh on anyone for complaining. Everyone should feel free to go ahead and complain and get it out of their system.