Do you remember Brokeback Mountain? It won 3 Academy Awards, and according to wikipedia, it is one of the top 10 grossing romances of all time. But have you ever heard someone say, "Gee, let's make some popcorn and pop in Brokeback Mountain"? No, you have not. This is a movie that is good for one required viewing, but it's not a movie that most people will want to watch again and again and again.
I don't mean to pick on Brokeback Mountain. Other movies that fit in this "just watch once" category include Million Dollar Babies and The Sixth Sense. For a variety of reasons, some movies are the equivilent of "one-view wonders." Of course some people feel the same way about the Grand Canyon. See it once, and you never need to go back. It might be the "bucketlist mentality." Watch it, do it, check it off, and move on.
On the other hand, people often watch other "lower quality" films over and over and over. Harold and Kumar Go to White Castle and Napoleon Dynamite are two examples that come to mind. Almost no one, probably, would argue that these kind of movies are better than movies like Brokeback Mountain, and yet they are somehow, if not better, then preferable. The question is, Why?
(I won't even go into movies like Final Destination, which are apparently good enough to recycle the same plot time and again in countless sequels. -- Basically, no one wants to watch Final Destination more than once, but some are eager and willing to watch the same plot with different actors and in slightly different contexts...)
What is your defintion for greatness -- related to the context of movies or otherwise?
"It takes a certain courage and a certain greatness to be base." -- Jean Anouilh