I am offended that Phylicia Rashad is playing a white woman’s role in “August: Osage County.” It doesn’t make sense that she would have white siblings and children.
Offended? Nonsense. Frustrated, surprised, confused, irritated, exhausted, outraged even: maybe. But what would the offense be? Your objection, is that it "doesn't make sense." So you're not offended, you're confused. But, there are some other things that don't make sense: people on a tall thing pretending to be people they are not, saying things they don't mean, wearing clothes that aren't theirs, pretending that you're not watching (except for that guy in the first scene, who talks right to you).
What is it about this particular convention that is offensive? I've written before a few times about color-blind casting, and I still think that as a convention it is perhaps too young to have become conventional, but I think that it will. When was the last time someone was offended by a convention of the theater? Christian moralists decried acting as dishonest until they exploited it to share their faith. Elizabethan nobility used costumers' demand to sell their once-used clothing to keep money and save face, and so turned a blind eye on the dangerous blurring of class distinction that the theater represented. Today race is a central issue in our culture and one to which both social conscience and social structure are bound. The topic here is an aesthetic issue that happens to deal with race so understandably then, the stakes are high. "Not making sense" works as an analysis of color-blind casting if you stay in the realm of aesthetics: this is an arguable position. But outside of aesthetics, a rejection of Ms. Rashad's performance will fall flat and hard.
Unfortunately, the letter's author describes Ms. Rashad as "playing a white woman's role" rather than "playing a white woman," which makes his argument seem like it's much more about taking jobs than about aesthetic possibility or so-called suspension of disbelief. So, this isn't an aesthetic argument and this person is a fool.
If this were an aesthetic argument I would raise this question: aside from whether or not we can "forget" Ms. Rashad's race, can we "forget" Ms. Rashad? The most powerful alienating factor in modern performing arts - and the one which no one talks about - is fame. As far as suspension of disbelief goes, who the hell on Broadway knew who Deanna Dunagan was before this play? Wasn't she just Violet Westin? But Ms. Rashad is instantly recognizable from her TV work with Bill Cosby and from her previous Broadway successes, including last year's Cat on a Hot Tin Roof. At least as meaningful as whether we can accept her as playing a white character, is how it is that we accept her as anyone other than Phylicia Rashad. I think the answer to both of them must be the same.