I staunchly disagree. Physical attributes are half the book. The differences between Andorans, Tierians, Shinerians, the Sea Folk, Saldeans etc. was vividly painted. As much as the differences in the cities, personalities, mannerisms, you take away from the story when you take the individualism from the distinct cultures represented. Each cultural people was given depth, pains were taken to describe appearances, heights, mannerisms, politics, hairstyles, clothing choices, how the homes looked. (IE tiles on roofs and bricks were not introduced to Two Rivers until refugees brought their new fangled different methods with them.)
The actors and actresses chosen are gorgeous and talented people - but the guy playing Perrin has no shoulders to speak of. How would anyone believe he had been years apprenticed to a blacksmith with his current build?
Of course people have preconceived notions of what characters are "supposed" to look like, a vivid picture was painted over and over. Thom, is supposed to be white haired and with long white mustache... if he was played by someone with brown hair and clean shaven it would be just as jarring and disappointing. If Tar Valon doesn't have fanciful Orgier nature inspired buildings and Cahrien doesn't have topless towers it will be disappointing. There wasn't much left to the imagination in the fancifully vivid description of Robert Jordan's world and characters because he spelled it out in painstaking detail down to embroidery and materials of clothing. If Faile doesn't have a hawkish nose and tilted eyes she doesn't match the description ground into the pages every time we read about her. If tinkers wagons and garb are color glaring and so bright and mismatched as to be painful to behold it will be disappointing.
What else are they going to change? Will Emonds field still be as isolated and prim or will the "stout two rivers wollens" turn into slinky low cut and clinging garments to show off the figures of the actresses... will they forget that the women's circle keeps things (prude) 'proper' and pre marital relations are uncommon, scandalous and typically sex means "now we have to get married " to two rivers folks? Because that wholesomeness is a theme over and over and plays part of the plot and the personalities of the Emonds fielders. A backwoods set of towns where the farthest most folks get is Tarien Ferry, would not have a cultural mix. Tam al'thor coming home with an outland wife was something major for the town to talk about. Nothing ever happens there and news is months old by the time it reaches The two rivers. A Gleeman or a single wagon merchant or A Lady was big news to set the simple small isolated town gossiping and excited for a month and more alone. It was a bland little hamlet of stubborn farmers who were cut off from the outside world. Any basic genetic drift would pretty much ensure that the locals would be pretty homogeneous rather than diverse.
I'm still excited that a series I've read the covers off of from so many rereadings is finally going to be made for the screen, I'm still going to watch it, I still fervently hope to enjoy it, but I sincerely hope that they utilize the source material more faithfully. Is it really asking too much to honor the author's arduous and painstaking details? GOT went south once they started deviating and taking liberties after the TV Series surpassed the books.
Personally it detracts from the diverse cultures represented in the story by ignoring the characteristics presented as regional and unique. It mattered enough for the story that pages upon pages were dedicated to describing attributes of peoples and places. So why throw all that out the window during casting?