Bertuzzi is on the team because when he's on, there isn't a player like him in the NHL. Period. He's 6'3", 245 pounds, yet he has wonderful speed and agility, and can make great moves with the puck at top speed. He controls the front of the net. He hits, he forechecks, and even when he isn't scoring, he can be the most important player on the team, because the opposition hears footsteps every time he's on the ice. (Witness first round vs. St. Louis in 2003, when he and Linden controlled the Blues defence).
Yes he's inconsistent, and can be a bonehead. But the common denominator of all players picked by Canada in recent years is an ability to elevate their play, no matter their role.
I am fully confident that Bertuzzi, with something to prove and (potentially) on a line with Thornton and Heatley, will showcase the dominance that we saw from 2002-04, and in spurts the last two seasons.