Journey into Imagination (Original or current) was never an Omnimover as it was not a continuous chain, but rather a four car train, that the cars rotated to face the preshow then back again. That was not changed for any of the versions. World of Motion only rotated slightly at load an unload for access. By the definition it really appears that the Mansions are the only ones that actually present the scenes by car positions and the rest are just Continuous Rides. Buzz however is a gray area as the riders can turn themselves to face whatever. My 2 cents.
The Omnimover is indeed a curious description of a ride vehicle. Technically, only Haunted Mansion(s), If You Had Wings to Take Flight, Phantom Manor and Adventures Through Innerspace were true Omnimovers; a vehicle which limited the riders point of view and could turn upto 270 degrees on it`s base. As a loose term, it can be applied to a continuous moving chain of ride vehicles;
Buzz Lightyears Space Ranger Spin; an upgrade of the original IYHW ride system, though the car bodies were modified to allow all round views. Since the rider controls the rotation it fails on both counts as a true Omnimover now as any unfolding story view is at the riders control, not the script. Further versions are the same, the ride body being a new build.
Spaceship Earth (where the cars turn 180degrees in 180top and deviate slightly during the ascent
Horizons (no rotation at all but they did tilt)
World of Motion (no rotation at load or unload, but they did rotate slightly during the attraction and also stayed level on the ascent and decent ramps)
Journey into Imagination (90 degrees rotation but the load and unoad chain would split into the 4 car train mentioned above) - a hybrid ride system too ahead of it`s time.
The Sea Cabs (no rotation; just a continuous chain)
There again, we call a hoover a hoover as a generic term when it`s one make of vacum cleaner so as a
generality Omnimover is any of the above ride systems.