The MPAA FORCED Léon to be cut by the distributors? I always assumed it was done because they assumed audiences wouldn't appreciate the quieter scenes. It's kind of sick that wouldn't give the movie an R because of these scenes, considering that they DON'T EVEN HAVE SEX. The violence wasn't that extreme, but I would consider it more offensive than two people talking.
Another example of an "unrated" version that is better than the theatrical cut is "Badder Santa," the uncut version of Bad Santa. I don't know whether the cuts were made for ratings reasons, but there's an AWESOME scene near the beginning, about seven minutes long, where Billy Bob steals a car, drives to the guy's house, and hangs around there (drinking, using the toilet, etc.). It may not sound that great, but trust me, it's hilarious, probably the funniest scene in the film.