It's difficult to argue with stats that Smith is as good as Bozak because he's never been given a chance on the #1 line. However, Kadri is a different story and undeniably much better than Bozak. Here are Kessel's stats with Kadri vs. Bozak at even strength:
Kadri
GF20 - 1.288
GA20 - 0.716
Differential - 0.572
Bozak
GF20 - 1.067
GA20 - 0.712
Differential - 0.355
Bozak is not this team's 1C. Kadri is.
Which is why some people argue to play Bozak there to have a balanced attack. Kane doesn't play with Toews to my knowledge, you see this all over the league.