Hmmm, lots of interesting stuff here. Dave, in case you truly are unaware of this unpleasant fact from U.S. history, for some reason, bigoted whites often make jokes about African-Americans eating chicken (especially fried) and watermelon. Frankly, I'm not sure where the stereotype came from because these are Southern foods, and my Southern white mother-in-law ate them all the time. Nonetheless, it is indeed an ugly stereotype, and it's not polite to make comments about eating chicken when you're referring to black people, unless you literally mean that they ate chicken. (Example of when it would be ok: food poisoning in a chicken outlet, and a news reporter interviews a bunch of customers, some of whom are black, about whether the outbreak will stop them from eating at the chain again). End of lecture.
Dave, you also wrote, "Also, Jews don't feel like they have to prove anything nowadays, because they are equal." I'm Jewish and don't necessarily agree with you. I remember that there was a huge fuss when one of the "Fiddler on the Roof" revivals not only failed to cast Jewish people in any of the main roles, but also, according to one critic, tried to portray the problems that the Jewish residents of Anatevka experienced as the poor versus the rich. The critic referred to the production as a Fiddler on the Roof "without Jews."
I do NOT believe that someone has to be Jewish to play Tevye. However, if Tevye is played by a non-Jew, he'd darned well better not be a straight-haired, blue-eyed blonde, and, if he is, he needs to wear a wig. And the actor had better have all the mannerisms down -- the stereotype of Jews of European descent talking with our hands came about because we do indeed use gestures to make a point. Spoken cadences are different from that of many other people as well, probably because of the influence of Yiddish. Most Jewish actors will "get it," but non-Jewish actors may not.
One final point regarding ignoring appearance when a story is adapted from a popular book: The book's fans become furious. For example, Janet Evanovich's comedic, romantic mysteries have a huge fan following. When "One for the Money" came out as a movie a year or two ago, I'm sure that I wasn't the only reader who noticed that Joe Morelli, the very Italian tall, dark, and handsome love interest, had become blue-eyed. In fact, the props department obviously missed the memo, too, since they ginned up a police report describing him as brown-eyed. NEVER mess with fans of a mystery series -- one of the first things I learned in my writing classes.
You alone can make my song take flight.