would Bush be better used as a WR like Steve Smith

That's kinda limited thinking. Reggie does so much for the team in the backfield, motioning from or to the backfield, pass blocking etc etc etc. Moving him to a single position would limit his effectiveness all a complete football player, and it would leave Brees exposed to DB blitzes.

Bush will help the team more from the RB position and he has the added threat of becoming a WR when the play calls for it.