I really don't think you've tackled the problem at the correct angle here. Anyone can assign two or more axis to rate things on and call it a better rating system than a one dimensional one because it provides more information. Viewers want more information before deciding whether or not a thing (in this case, a movie) is worth their time. While your two dimensional rating system may work for some, this specific system is only justified for people who want information on "quality" and "rewatchability." For example for a person like me, I don't rewatch movies so the "quality" axis offers me way more value and insight compared to the "rewatchability" side.