Why hasn't Luck been to the SB? According to you, great QBs can carry average talent. I have never actually seen that. Which QB has ever done that? Are there examples? Maybe the Broncos teams of the 80s with Elway. Maybe.
Cousins has done very little to show he can overcome an average defense, which large contracts tend to do to defenses. Rodgers has not been back to a SB since 2010 when their defense is number two in PPG. Not even the best QBs in the NFL can do it. Cousins will be able to do it? No way.