That is true, but I think there is a difference between selling merchandise of a great attraction and changing or creating an attraction mainly because of merchandise. While the end product seemed to have turned out ok, I think that many people feel that these changes weren't made to plus the attraction as much as they were to push pins and plush.
And instead of plusing the attraction the same way they did the Haunted Mansion, by adding completely original ideas, they took the easy way out. Now if what is created is at least done well, then I don't think too many people are going to mind or complain. And personally I feel they did a fairly good job on this update. I think they could have definitely used the money wiser, but I don't think they screwed the place up either.
Many of us believe that the parks are at their best when the Imagineers are allowed to come up with their own stories. People like myself grew up with EPCOT Center and saw that you don't have to be familiar with an attraction's cast or story in order for it to be successful.