Meta: I find myself constantly refreshing the link to see the new comments are posted.

Dopamine at work!

Of course it is! But this piece actually presented a fairly good set of design principles, albeit unethical ones according to some. I particularly fancied the discussion about unexpectedness, which, in turn, is related to the unpredictability we've discussed, whether in terms of iterated expectations, game theory, cyber security, chaos theory, pscyhoanalysis, or something else.