Even fantasy should have some grounding in realism, and realistically an isolated backwoods community is going to be homogenous. I know, because I live in the same little backwoods community where my ancestors were among the first white settlers almost two centuries ago. Today we have automobiles and means of communication with the outside world, but in my grandparents' day, the only people available for marriage were cousins. Traveling thirty miles was a major undertaking, and most people lived their entire lives without straying that far from home. No matter the diversity of the people who originally settle in a place, it only takes a few generations of such isolation before everyone shares the same skin tone and basic features. I thought Jordan did a pretty good job of setting the tone for Emond's Field in the very beginning of the series. It was very poignant that strangers were such a rarity, that Rand was clearly different from his neighbors, and that Tam was a man of mystery for having traveled in the outside world. Rafe is making an asinine attempt to apply metropolitan standards to a rural community. He is clearly pandering to someone, just not to fans of the source material. Such a fundamentally illogical choice in casting does not inspire confidence in the rest of his (re)vision.
Admittedly, many of Jordan's characters possessed interesting mixes of traits, enough to make casting a bit of a nightmare. For example I always imagined Lan as a blue eyed Mongolian (admittedly the cover art influenced this view). And good luck finding thousands of deeply tanned redheads to play the Aiel. The Seanchan had racial diversity because their empire covered an entire continent. So I have no problem with racial diversity where it is appropriate, but the Two Rivers was not the proper place for it, and injecting something so illogical and unnecessary into the opening scenes sets a terrible tone for the rest of the series.
I'll simply have to content myself with the books, as I am not interested in having an agenda foisted on me at the expense of my love for the series. I'm sure there will be plenty who will enjoy the bastardization of Jordan/Rigney's creation, and more power to them, but it is immediately evident the showrunner has no interest in creating a remotely faithful adaptation. These books have such a huge fan base that could have been directly transferred to the tv series, but I can see from other comments that I'm not the only who has been alienated before the first episode aired.