Because Wade has taken Smith’s job as the Cavaliers’ starting shooting guard.
Joe Vardon of Cleveland.com:
Smith is a better 3-point shooter and defender than Wade, making Smith a more natural fit next to LeBron James and a maybe-more-ball-dominant Kevin Love. But Wade has chemistry with LeBron after their time together with the Heat, allowing the pair to mesh better than their styles would suggest otherwise.
Wade is far more accomplished than Smith, and though current ability should matter, so does stature and ego. I also wonder whether the health of the 35-year-old Wade factored. Some players his age have trouble getting loose after sitting to start games.
If Derrick Rose exits early to lead reserve-heavy units (what his role should become when Isaiah Thomas returns) – with LeBron and Wade presumably leading the playmaking between – this might open the door for Richard Jefferson to stay on the team. The Cavs are in a roster crunch, but this rotation would leave less of a role for point guard Jose Calderon. Perhaps, this opens the door for Cleveland to waive Calderon instead of Jefferson, who has been useful on the wing against the Warriors in the Finals.