I think the disagreement here, though, is how strict the themes of the different lands in Magic Kingdom are in terms of representing specific times and places. To me, the genius of the model established at Disneyland is that it features a collection of themed lands broad enough to include a range of different experiences under an umbrella of, say, Adventure, the Frontier, Fantasy, and Tomorrow/the future. The complaints about Tiana not fitting seem to be retroactively imposing far stricter limits in terms of geographical (and geological) accuracy than ever existed in the park. Certainly far stricter than when they added Splash Mountain in the first place.
If anything, I think Disney has wandered too far away from this model to the other extreme of lands dedicated to one specific IP which really box them in regarding what they can add. Tomorrowland, for example, could feature Buzz Lightyear, Star Wars, Stitch, and, if it is a hit, an attraction from the new Strange World film. If Strange World is a hit, however, there's no place for it in the new 'lands' they are building such as Toy Story land, Galaxy's Edge, Pandora, Cars Land, etc.