The problem is, even the most spectacular algorithm becomes stale or at least unimpressive for human perception.
I spent 10h+ in Shadow of Mordor just running around marvelling at random Orks and their designs and their traits and their names. But after some time, you see repetitions, not whole characters but the same face, the same title, whatever, and it just gets boring.
I was blown away when I created my first DF world, and while it's still pretty cool to have thousands of "people" simulated, once you get a grasp of the limits, it loses some of it's magic.
Or look at Spore, where the millions of different player-created species on thousands of planets in your Galaxy had no impact whatsoever.
No Man's Sky will need a damn lot more than just random planets to be an actual game.