While I don't disagree with you, I personally don't think an "interesting plot" is necessarily important for a good movie. Really....The only question is whether someone decides it will be interesting enough to make a movie about.
Don't get me wrong -- A really interesting plot can in fact be part of a good movie. However, so can a simple plot. I've always said that the difference between a good movie and a bad movie is not the plot, but the execution of plot.
I've seen films with simple plots that have been very well done and enjoyable, and I've seen films with fantastic plots that were executed poorly (and thus the great plot wasted). In fact, I think I enjoy the simple plots more. Maybe those films are just "cleaner" in my eyes.