I think it's even simpler than that. On the round table from the Blu Ray they pretty much tip their hand.
T'challa could be black James Bond.
James Bond has a Q, T'challa should have a Q.
I suppose they could have used Taku or W'Kabi but Shuri is a recognizable character from the comics and needed a role that set her apart from the other women who all have something to do. Boom. She's "Q".