[Matrixbeast]

Man, I loved the unmorphed scenes in Kakuranger. Helps you feel like they're real martial artists~

Anyway, the easy answer to this question is to sell toys (They don't sell unmorphed actor toys, after all )

But I think it's to let them get away with larger stunts and action pieces. Unmorphed, all the actors can do are flip and throw punches and kicks. Morphed, they can bust out the weapons, the enemies can throw bigger attacks (Since it's easier to believe the ranger in suit can survive such an explosion now), they can get to the special attacks (Which usually just relies on CG rather than on screen acting), and they don't have to re-shoot an entire fight scene if an actor flubs a line~