I agree there is no reason to think he didn't work hard in the off-season, or other off-seasons. It also seems clear that both the coach and the front office don't think this is as important as fans do, or at least, are more patient with someone who is still a very young, if high-paid/high-expectaton player. NBA teams barely practice once the season starts so I wouldn't expect magic at this point.
He can be better, but at some point it's a bit like wishing Rollins would be a walk-machine, or Howard would strike out less (or hit singles away from the shift). It might not happen, and maybe that means Simmons isn't a league-MVP caliber player, just an All-Star. Great players are also a bit psychotic in their focus and desire to win (Jordan, Kobe) and I'm not sure Simmons has that - he seems like a nice kid. But there are a lot of years left before we'll really know what he can be.