As I read more from and about Plato, Aristotle and their times, it becomes clear to me that these two political philosophers did not mark the height of Greek (or Hellenistic) civilization but the demise of the Athenian culture.
It simply is incorrect to lump in the heterogeneous city states of Greece and argue they represent an homogeneous Greek (or Hellenistic) culture. The tendency to do so is most likely the legacy of Roman historians, who could not help but to think of Greece as a prior Rome. Moreover, what Plato and Aristotle did amounted to nothing more than a post mortem of Athenian culture to identify what had gone wrong and how to correct it going forward.
Plato and Aristotle did not come to praise Athens, but to bury it.