So I typed into google: 'How tall is Stephen King" and the answer was 1.93m which is 6 foot and 3 inches which is incorrect.
Then I typed in : how tall is Idris Elba and got 1.9 meters which is 6 foot 2 inches, now Roland was based on 'The Man with no name' so he should be 6 foot 5 inches.
Now I typed in: how tall is Tom Cruise? Answer: 1.7m which is 5 foot 5, but Jack Reacher is 6 foot 5. So height has nothing to do with who plays a character. Colour of skin shouldn't either unless it totally ruins the storyline or makes the story ridiculous. I would have reversed the roles and have Elba as Walter and McConaughey as Roland.
Jack Reacher fans were outraged about Cruise portraying him. In the Jack Reacher books, his intimidating physical stature and strength is brought up numerous times. I will say that the first Jack Reacher film was still very enjoyable despite the change. It added a different element of guys underestimating him when it came to fighting instead of guys seeing him and being immediately intimidated.