It seems to me like "rewatchability" isn't really a useful metric when I am looking for a new-to-me movie to watch.

And when I am looking at user rankings for a movie, almost by definition I am only concerned with rankings for movies I haven't yet seen, since I already have an internal self-ranking for a movie I've seen already.

Histograms are extremely useful for knowing the spread of rankings, which the scatter plot also illuminates.