I know this doesn't make for as much fun as taking either of the two extreme sides here, but yes, Smart's defensive intensity and some nagging injuries springing out of that probably helped to put a damper on his already mediocre shooting stats.
His poor shot selection probably contributes as well. It has been pretty clear for those watching him that he has drifted in and out of a decent shooting form through his first two years in the league. That still elusive form does give his boosters a fair basis for hope, at least.
He's probably not going to give up his defensive intensity (and possible propensity for nagging injuries coming from that), but he is still fairly young and so it is reasonable to expect that he will get locked in to his better shooting form, at least, somewhere in the next year or two. Also, there should be some hope that he'll stop taking so many questionable shots.
Put all those together and IMO it is reasonable to expect him to attain at least an average, if not above average, shooting ability. His ability to get to the hoop and score there, one of his strengths in college, may be the greater concern on his offense, however, since after two years of heavy playing time he still seems not to have, what--the handle or the speed?--to be effective there at this level. This may limit his effectiveness in playing point here too, which doubly increases the importance of his getting his shooting locked in from what well top out as his combo guard position at the 2.
So I think it is fair to grant his exceptional defensive ability and overall scrappiness and crunch-time impacts. Improvement in his shooting should be expected this year or next year at the latest--while still young and on his rookie contract. But to expect him to become an exceptional shooter or to develop an exceptional all-around offensive game at this point is more in the realm of optimist hope than balanced expectation. Still may happen, but probably not more likely than not, if you will.