Good movies use the entire frame. What's missing very often alters the actual content of the scene. If a character is isloated by the director in the corner of the frame to show their alienation you will not see that if they are panned to the center of the frame. Throw on 'Rebel Without a Cause', 'Ben Hur' or 'Lawrence of Arabia'. They are literally unwatchable in 'slice and dice' (pan and scan).
Unwatchable unsmatchable... back in my college days, all I had was a small 13 inch TV, and a gigantic 10 year-old VCR. Back then, Music Plus was renting videos for 49 cents a pop. I'd get boatloads of them, and enjoyed watching them even with the crummy setup.