My biggest concern about Brooks is I rarely see passion, only anger. That type of person is not a leader, Kemba is definitely a leader. In fact, he's the kind of leader that does it for the right reasons. Also, as has been mentioned, Kemba is a much stronger and much more physical player than Brooks. He may not be quite the leaper Brooks is but even still he's an excellent rebounder because he simply understands the game.
If you want to make the case that Kemba is not as important to this team because we already have Brooks, I could agree with that. Not because they are so similar though, merely because they play the same position and do SOME of the same things. Add in the fact that if we keep Brooks, PG is no longer anywhere near our most glaring weakness and I could see drafting someone else. However, despite the fact that I think we undervalue a healthy Brooks, put Kemba and Aaron on the same team and Walker wins the starting spot and rather easily, IMO.
Steve