Disagree with the premise. New movies tend to have more plot holes, less characterization and worse writing. Improved effects only rarely make up that margin. I also find the following stories just as plausible as yours: "New movies are over-represented on the IMDB top 250 because they get bolstered by excited fans who just saw the film and haven't yet taken the time to digest the movie or see how it dates and who, often, haven't seen the old movies on the list." The Return of the King is not better than Blade Runner.

/done with my silly arguing for the day.