I don't consider him a very good finisher, either, but you're probably overstating that a bit: he's shooting 65% at the rim this season. (Only Lydon's finishing better.)
Roberson's showed that he can hit a 17-footer (not good, but adequate), though it's been a long time since he's attempted one. Again, that's not the first, second, or third option on offense, but it certainly should be an option when he's on the floor. We've seen the result when teams scout us and are told that he's not going to take that shot - they cheat and double the post.
He's been very good for three years in pick and roll situations. Unfortunately, Frank Howard seems to be the only Syracuse player who can initiate a high pick and roll; with a couple happy exceptions, Gbinije gets totally frozen when the hedge steps up on him.
He's occasionally initiated his own offense from the high post, either driving to the rim for a layup or dumping the ball to the post (he, Coleman, and Lydon are all good interior passers.
He's able to present a threat in each of these ways. When he gets no touches, he's a threat in one way: as a garbage man. And surely I'm not the only one who noticed that Louisville and Pittsburgh essentially face-guarded him every time we put a shot up, giving up a potential defensive rebounder to take him away from the glass?
Other teams have adapted to take away what he does well. We could have recognized this and tried to exploit those changes. Instead, Boeheim criticized his limitations, further limited his role and minutes, and then criticized his lack of production in a game that he was drawn out of. It's so strange that there are so many posts on two sides of what looks like a fairly black-and-white topic.