You railed at one (HHCom) writer for mentioning a Jewish character that didn't have any apparent reason to be Jewish. Is it considered poor taste to have some characters in a large cast be non-WASPS primarily for the sake of diversity? Or is it just poor taste to call attention to a character's ethnic/racial/whatever status in a query and/or synopsis?
My objection is that "the doctor who was a Jew" didn't tell us anything we needed to know in the hook and thus comes off as using religion to describe something that didn't have anything to do with religion. Would "the doctor who was a Zoroastrian" be seen the same way?
If the doctor couldn't work on Friday cause he's Hasidic that's something that adds to the plot.
It's like the newspapers that used to mention race ONLY if the subject wasn't white, as if white is the default setting for race. You'd find it hilarious if everyone assumed people were female unless otherwise indicated (females being the majority).
I much prefer a writer using assumptions against expectations. One of the most brilliant uses of this was one of Harlan Coben's Myron Bolitar novels; I forget which ones. Harlan Coben is actually a master of using your expectations against you. I'm not the rabid fan of his stand alones that I am of his string of Myron books, but I do think he's a fabulous writer and story teller.