Discolsure: I am a co-founder for a movie recommendation site called tellmetwin.com so I am biased towards our own rating system...

I have never considered the rewatchability criteria as a potential factor in rating a movie, but must admit that is has appeal. But thinking about it further, it is a very personal metric so would not be very useful in determining the overall watchability of a movie. I.e. if you consider a movie rewatchable it might not correlate with me considering it to be watchable.

I would love to be able to see a plot of individuals and how their ratings cluster (some interesting visual way of adding and removing individuals would be cool) because I would guess (based on our own data) that these plots would not be uniform. And if they are not, then an individual's movie recommendation, based on rewatchability, would have less value to me.