I'm sorry, but I think most of this is just excuses cuz we dont want to admit it was a mistake. Hindsight is 20/20, but for right now, it's looking like a huge mistake.
1. Brooks is getting a lot of time, because when he was given just a little time, he did a lot with it. He is being asked to score, but saying he's "scoring without conscience" doesnt make sense if you watch him play. He is scoring within the offense (what little they have). With the weapons he's shown (midrange, hesitation dribbles, floaters in the lane, 3pt range, etc), he could score 30 if he wanted to play "without conscience". He is playing confident, but he isnt forcing anything.
2. Brooks isnt a bad defender. That would be an easy thing to point to, as an excuse for why Doc wouldnt play him...but its just not true. If all you see is his boxscore stats, you might think that, but he's not a bad defender. On the other side, everyone assumes JJJ will be a good defender, but thats no guarantee. In college he played against weaker competition, and has a size advantage that is gone now that he's in the league.
3. Saying it's easier on Brooks because of his position, doesnt make sense. Its a guards league right now. All the elite players are at the wings. Thats who Brooks competes with every night. A half decent big would find it easier to have success in todays NBA, than a good wing player. There's no reason a pf should be "expected" to accumulate more fouls than a wing...especially if playing against lesser players every night. Just playing the PF position doesnt mean you automatically have greater defensive responsibility. Most teams play man...thats a 1-on-1 responsibility for everyone. Maybe a Center that anchors the defense like Chandler/Perk/Bynum has a greater responsiblity, but a PF known for playing away from the basket like JJJ would never have any extra defensive responsibility.
The main reason Brooks is excelling and JJJ has yet to play, is that Brooks already has the physical gifts and skills to beat his peers, and JJJ doesnt. JJJ has a great handle and shot for a PF, but he seems to be too weak. At SF, he'd have a size or strength advantage, but questionable dribble and speed. Until either his stature or skill set develops to the point where he can fulfill all the requirements of a position, Brooks will be superior.
No matter how many minutes they both got, Brooks would come out on top this year. It was easy to criticize his game when he was just scoring on bad teams, but he did the exact same thing to use. Unless you want to say that we're an equally weak defensive team to those he played before, I think he should be given his due credit. So far, I think he's competing with Ricky Rubio for ROY