At slickdeals where the wbshop sale was posted (25% and 20% off deals have expired), there are many who complained about having to swap the disc for Extended Edition movie. Reality is if WB chooses to release Ext Ed on single disc per movie, there will also be complains.
What WB should do is when they are ready to release the Ext Ed trilogy as individual movies, they should use a lower bitrate to compress the movies tighter to single disc per movie, and also keep the 2-disc per movie trilogy in the market. That way, those who don't want to swap disc during the movie can choose to buy the single-disc movie with lower quality. With individual movie usually sells for higher price than the cost per movie in the trilogy set, that should cover the cost of re-authoring the movie to single-disc. But will WB willing to put extra efforts in trying to satisfying different types of buyers?