I would call that criticism. And I would like to iterate that Joseph has, in fact outplayed 3 players who have practiced at that position.
Considering the overall success of our offense this year, Joseph is not as bad as people make him out to be, and Robinson's lack of playing time isn't a reason to hit any panic button ... yet. Now, if he's not starting on the offensive line somewhere next season, I'll share your concern.
But for now, judging by the fact that he's practicing at both tackle and guard, my guess is that Fisher is using him as a backup to both starters, at which point, I'm sure the offense could change depending a lot on the defense they face, but I'm thinking that they like the balance they can throw at defenses now, and I don't blame the coach or coordinator for that decision.