Yes, we all would have preferred a brand new ride system and we would all prefer every new attraction to be ground breaking but that's simply not realistic. Nothing in Disney's history has led us to believe that would ever be the case. Even those of us the reminisce about the good ol' days aren't that delusional. Not every attraction can be an E-ticket because then the definition of that type of attraction would change.
As for Mermaid being a book report - isn't that the point of any Fantasyland style ride?
Actually, a lot of Disney history makes us think that they would develop a new ride system. Look at Indy, they were going to go with a mine train ride, but changed it to Jeeps because they felt it would be derivative to Big Thunder. Disney makes a conscious effort to develop new ride systems, or at least different ride vehicles.
We're not talking about doing something impossible, or even "ground-breaking" but developing a ride system which is different from those used elsewhere, perhaps a variation. This wouldn't cost millions and millions of dollars. Sure, some ride systems were duplicated, especially when they were just starting building people eater rides, they came up with the boat system used in Small World and Pirates, but didn't really use it again at Disneyland.
Tony Baxter, who worked on the Fantasyland upgrade in Disneyland, didn't go for the straight "book-report" rides, he added stuff not in the film, but which would make a ride interesting, and be in that character's world.
I still feel perfectly comfortable saying that the Omnimover system doesn't work well for Mermaid, and that they should have gone with something else.
Restricting field of view is OK in some circumstances, but on Toad you've got 360 views and on Mermaid it is 180 . . . yet you can still look up and see the ceiling and all the lights.
It was Eisner who said that rides trick people into having a good time and that nobody would ever "look back" on a Disney ride. If you know where to "look back" on Toad you can Sherlock Holmes in a window and other cool stuff.