But consider: perhaps the fact that the Courts are so like Amber was intentional, a comment on "human" (sentient?) nature. Let it be reflected in the Unicorn and the Serpent, or the Pattern and the Logrus, in terms of what they can do, abd there's a serious comment on the nature of difference and experience per se.

That's certainly possible. My finding it disappointing is not evidence of anything other than my own disappointment. :)