"For one, a Black Cathy and Jamie feel like a novelty, given how many productions cast white leads by default. "
This is the sentence that seems to be causing your upset. Please note, there is nothing in this language that suggest the default was wrong or racist, just that it was the default. You are pointing out many reasons for this default; the author of the review did not choose to belabor that point. She also, rightly, says that the casting still feels novel, a word that I think carries less charge than you are giving it.
One aspect of reviewing a show is reporting on what a reviewer sees. This sentence is accurate reporting.
I understand given the charged nature of race in our current conversation about theater and otherwise that it has set your mind on other paths, but please re-read the review.