This is because everyone born after 1927 grew up with movies being shot in 24 frames per second, which has hardwired our brains into seeing that frame rate as the cinematic one. As a result, watching movies in any other frame rate can feel unpleasantly weightless and unnatural, like a dream about your father making love to a balloon animal.
So if we want cinema to look cinematic, there's really only one option: Set fire to our TVs. Or switch motion smoothing off, but that's often a lot harder. As Cruise and McQuarrie note, even if you realize that your TV is barfing out soap opera effects, manufacturers have made it pretty tricky to turn that off. Even those of us brave or suicidal enough to venture into the Escherian hellscape that is the Settings Menu likely won't find a motion smoothing setting. That's because, like a dictionary salesman posing a riddle in a cave, most big brands use their own obscure, meaningless buzzwords for the setting.
Luckily, now we have Tom Cruise in an old-fashioned PSA telling you to goddamn Google it. Just remember, when you forward this video to your parents, tell them not to maintain eye contact with Cruise for longer than ten seconds at a time. Otherwise, they risk serious overexposure to harmful Xenu rays.