I think Chiwetel Ejiofor could have played a great T'Challa, but the outcome would have been the same imo. T'Challa was much more "badass" in CW because it wasn't necessarily about him, it was about Captain America. The protagonist has to have flaws and weaknesses because that's all apart of the hero journey. Black Panther is always going to be shown as vulnerable in his own movies because the lens is focused on him.