(On the other hand, SF's readability kicks Helvetica's ass, so at the end of the day, I do welcome this change. But Apple could do so much better.)
[1] FF DIN, an adaption for use in graphic design: https://www.myfonts.com/fonts/fontfont/ff-din/
[2] See e.g. http://spiekermann.com/en/wp-content/uploads/2012/02/helveti...
And those brains are pretty predictable; you can figure out what someone's "tastes" will be from their DNA and formative experience far in advance of actually exposing them to the stimuli in question.
Or, to put it another way, "human aesthetics are an arbitrary result; they 'could have' been anything. That doesn't mean you should ignore them—your arbitrary path-dependent values are literally all you are."
(This is just the aesthetics interpretation of the LessWrong http://wiki.lesswrong.com/wiki/Metaethics_sequence, if you're wondering.)