I emailed about this to request that they kindly reconsider this recent change, and I received a return phone call. The cast member was very pleasant and apologetic but confirmed that they indeed no longer will honor DisneyWorld tickets at Disneyland. She said it is because they have two different ticketing systems. (It seems to me like they have enough technology to support this kind of thing if they really wanted to.) I expressed my unhappiness, especially because DL does NOT offer the variety of tickets (including non-expiring) to select from. I've spent many thousands of dollars on dozens of trips to Disneyworld, but I guess Disneyland won't be receiving a visit or any $ from me!