Have you actually been on DL's Submarines w/ Nemo? Few of the AAs are full-motion ones.
True but still more AAs than epcots version
It has a "cohesive story" because it basically retells the movie. Also, the attraction barely ties into Tomorrowland; the voiceovers merely mention "listening to the fish" at one point.
The story is similar to the original Submarine Voyage. In the original you board a submarine for a voyage to the north pole...this time you board a submarine for a voyage to an active undersea volcano (which was also from the original ride). The retelling of finding nemo is really just an eleborate subplot in the attraction. It ties to Tomorrowland because the focus of the attraction is still about marine research and deep sea exploration something that will play a bigger role in our future.