First of all, Roberson played a hell of a game yesterday, and deserves all of the accolades and praise that gets.
Second of all, I think that much of the disappointment is due to the expectations that many had for him coming in. I don't think people realize that he was rated higher, for example, than Tyus Battle is currently on ESPN. He was a top 35 recruit nationally. That may not be fair to him, but how would people feel if Tyus Battle was a non-factor his freshman year, only got to play significant minutes his sophomore year because of an injury to another player, and then still struggled greatly with consistency half-way through his junior year? Given how many people on the board think that Battle is going to step in and be better than G his freshman year, I think they'd be EXTREMELY disappointed.
Even just recently, Roberson still forced us to play 4 on 5 at times as he'd receive the ball around the elbow with the defense scrambling and would take three hesitation dribbles out to the three point line. We might expect that from a 3 star recruit a la Baye or even Rautins, but not a borderline 5 star recruit like Roberson. Now, I don't think that's very fair, especially since Roberson hasn't demanded the attention of a star, and has seemed to have a very good attitude consistently, but I think that is the explanation for why so many, including myself, are left wanting more from Roberson.