You're both right. Obviously Shepherd's outside shooting was probably at the top of their list of attributes that compelled them to take him at 3. But his athleticism, and his handle, combined with that shooting, is what put him on theirs, and others, "1st Pick" lists in the first place. There are probably hundreds, if not thousands, of similarly skilled shooters in every class of kids. He separates himself with the other ball skills, and then further separates himself with his elite athleticism.
Having said all this...he's averaging around 12 minute per game of playing time, less than 4 points a game...and isn't even close to being in their main rotation. Sooo...evidently they didn't need him as much as it seemed when they drafted him at 3.