Its a policy that goes way, way back (even all the way to The Dead Guy). It used to be called plussing. The idea is simple any show is going to get old if you see it over and over and over again. So to keep rides interesting,
Disneyland would go through and add new show elements or scenes to the attractions. They were never announced or advertised; it was just something that was done during a rides annual rehab.
The last plussing of Disneylands Pirates of the Caribbean happened several years ago. Several figures from Epcots World of Motion were placed in the ride some just on a corner, other as a major show scene. The best known were a couple of pirates lifting a treasure chest up the waterfall exit further up the water fall you saw that they had turned into skeletons. It added a nice beat that helped round out the story.
In the past, WDI usually had final say over the look of any attraction. Usually, a tweak in one park would end up in the other it was a good way to spread the best ideas. However now that WDI no longer really exists, each park has more control over how much plussing gets down.
The large majority of Disneylands guests still come from the Southern California area. There are a huge number of annual passholders and even normal people still visit the park once a year or once every two years. Plussing and enhancements to existing attractions are vital in keeping coming back time after time. As was mentioned, even after the inclusion of the DVD commercials into Pirates of the Caribbean, Disneyland also added several new elements to The Haunted Mansion just to keep the ride fresh (and better yet, they had nothing to do with Eddie Murphy).
Walt Disney World, however, thinks they have a different guest. In the past, most guests were either first time visitors or hadnt been in the last five years. The shows and attractions didnt grow stale as they would for people who see them every year. Therefore, plussing was fairly rare and was really done to improve the rides show.
But the last decades focus at WDW has been to shrink the time between visits. Cheap motel rooms, annual passes and timeshare condos have now built a large block of guests that visit once a year or even more frequently. Normally you would think that this would make WDW act like Disneyland change the rides to keep the guests interested.
Well, the truth is WDW doesnt want to spend the money. As witnessed by this years cancellation of the Country Bears Holiday Show WDW is pretty well convinced youre going to show up anyway. As they see it, for over five years now they have been closing attractions and reducing service levels, and everyone still came. If people dont mind about the cuts, they certainly wont complain about not getting additions. Every dollar they dont spend on maintaining or changing a ride is another dollar that be given to ABC.
In direct answer to your question, I would expect to see non-movie changes at Disneyland, but the only changes youll see at WDW are those that are paid for the Disney Studios home video marketing department. The next round is supposed to happen this spring for Will Turner and a Elizabeth Sparrow figures to go in somewhere. The next hope is that
Jungle Cruise The Movie is a big hit.