I'm going to start off this by stating: i haven't finished the novels, however, unless it's established lore BY THE AUTHOR himself, then what's the complaint.
I am sure everyone that has ever read The Dark Tower series and saw that horrible "movie" get what I'm saying here.
In the novels, it is very well established by KING that Roland is a tall, skinny white guy. It's like a major subject in the second book.
The movie decided to cast Idris Elba (who did a great job, but was still wrong for the role). But, at the same time, to cover this argument, King kind of went and messed up years of theories by stating that he was a different Roland on a different level of the Tower.
Which has never made sense to me but I always consider it being the same journey but maybe with actual lessons learned or slight changes made. But then I saw that terrible movie and understood why he would say that.
I hate to say I was glad it wasn't successful because of a lot of different reasons. See, in the second novel, a black character comes into play and she's got all kinds of issues with white people (rightly so in my opinion) at first.
If the movie had actually been successful, I have no earthly idea how they would set all of that up. They probably would just have to drop the character (which is sad because she has awesome development).
So anyways, if it were an issue because it DOES play into future story lines, then yeah, I'd get the issue. If it bears no significance to the plot or at least some of it for other character development? Then oh well?
There is a difference.