Eh, CHICAGO is different - it is always changing, yes, but the wardrobe does not strike me as "costumes" (most of them) so much as stylized dance wear. You don't think "Roxie Hart - black lace leotard!" like you do "Anita - purple dress!". That's their schtick (the changing) - they have to do something to counteract all that black. CHICAGO is not at all to what I'm referring but appreciate the example.

And I get changing a costume, choreography, etc. to capitalize on an incoming actor's strengths and to minimize other areas (i.e., the Fairy Godmother's costume in CINDERELLA).

But those types of changes seem to be necessitated by a rationale - and do not always have to be a great departure from the original design.
In my opinion, it seems a bit drastic and maybe unnecessary to change, say, Christine's wig color just...because, or, at least, not for any apparent reason. Of course, POTO is an industry on its own and can take any risks at this point. The Slave Girls could twerk and people would still come. Curious, is all.

The new Morrible dress seems to be the exact same (highly) flattering cut that accommodates many body types, same details, embellishments, etc...just a different color. I wonder who makes that type of call. I know there's no right answer - just interested in how it would come about.
Would the costume designer have to approve such a change or have any say-so?