I see what you're saying about the casting of a white President. But at the same time this could've been an opportunity for the show to cast an Asian, Latino, or other non-white President.
Kerry Washington's Pope did get on my nerves a little in terms of being so in the know and everyone loved/feared her, however her emotional breakdown at the end helps add dimension to the character. She's not going to be a Mary Sue.
I also question why the young white girl is a part of the team. I can see what the show is probably aiming for, with her being the heart, the moral compass of the show, and the gateway person to take the audience into Pope's world, but the character doesn't seem to possess any special knowledge or gifts that would make Pope want to hire her. And she didn't have any special insights or deductions that would show that she's really a genius or something, at least in the pilot. Maybe she has some deep dark secret, she's not all sugar and spice, or wild eyed innocent as she came across in the pilot.
As for Columbus Short I don't see him as muscle necessarily, but more like a rock, a steady, supportive presence for everyone else. He came across like an NBA sixth man. I don't see him becoming confrontational because black men who are confrontational-unless it is in the defense of a white person-isn't going to play. I can see him being the reliable, perhaps light-hearted, mentor, but not someone knocking a lot of heads. Pope and the British (?) guy will be doing a lot of that, IMO.