I can't see how this squares with box office returns. There are many bad sequels each year, a few great movies (as defined by critics or whichever elite), and lots in between. And the bad sequels tend to make orders of magnitude more money because way, way more people want to see them.
Further, from movie studio's cost perspective, isn't it easier to produce a good movie? For the cost of a single vapid summer blockbuster, they could hire several dozen acclaimed directors to each make their own dream film. But they don't do this because those films would not be nearly as good as an investment.