Many reasons:
-A Nigerian voice for a Nigerian character (athough there are exceptions)
-Feared that Crews's energetic spirit is not suitable for a rather calm stragetic villian.
-Sahr Ngaujah's performance is damn fine.
Those are what I though.

I did notice that just how he looks and how he would handle in combat does not fit thematically with the idea of a calm strategic guy. He is using a giant fist and a laser knuckle weapon. None of those strike me as particularly strategic weapons that an evil mastermind would use. When I think "Big guy who smashes stuff" I think of a loud guy who loves fighting. Doomfist's ideals of "Making people stronger through conflict" also fits someone who would be more energetic and eager to jump into any fight they could.

It just strikes me as a conflict of visual, gameplay, and story design which leads me to find it odd and unappealing for a character.