Some of these teams are way too loose with which numbers they retire.
The Blues retired MacInnis and Pronger simply because they were hall of fame level players and played 9+ seasons for the Blues. Kind of ridiculous, along with the other 6 numbers they retired. Brett Hull's #16 might have the only good argument for number retirement in St. Louis.
As others have said, I'd much prefer teams honor the players with a banner + number, but not retire the number.
Retiring numbers should be for only very special occasions where you have superstar players who played the majority of their career with a team and had success. Like Crosby's #87 in Pittsburgh or Ovechkin's #8 in Washington.