So, bringing it back to the B&tB Sing-Along: No, this was not the result of “they’ll like it because it’s Disney,” but instead the result of the directives and limits they were given. These were including, but not limited to, putting an Intellectual Property in the IdF Theater, no alterations to the theater other than new projectors, new projectors, limited budget, no actors, etc. This was the best that they thought they could do given the constraints.
Don't you think that's partially because of a "they'll like it because it's Disney" mindset?
Not from Imagineering, but from the higher executives that set the directives and limits you mention. It reminds me of the decision to sell the same Mickey Mouse etc. stuffed animals in almost every store in all four parks.