To those asking why #11 wasn't retired already, some context:
As noted, Maki played for the Canucks from 1970 to 1972, when he retired due to brain cancer, and died in May 1974. At the time of his death only one other player had worn #11, Chris Oddleifson, who was traded to the Canucks in February 1974. After Maki died he was asked to switch numbers so they could unofficially retire it, and he did, going to #14 for the rest of his Canucks (and NHL) career, which went to 1981.
Now why didn't the Canucks outright retire it? That is something Frank Griffiths would have to explain, and seeing how he's been dead for nearly three decades I don't know if we'll get any answers; neither do I think his son and successor as owner Arthur will say anything about that.
But I do have thoughts on it. Consider the era: it was 1974, and the number of retired numbers league-wide could be counted on your hands (there was 8), and if you look at the names, a trend is noticeable: Ace Bailey, Lionel Hitchman, Howe Morenz, Dit Clapper, Eddie Shore, Maurice Richard, Jean Beliveau, and Gordie Howe (I suppose Larry Aurie was also technically retired at this time, too). Aside from Hitchman (and Aurie) all of them are in the Hall of Fame, and are all some of the biggest names in league history. Wayne Maki was clearly not in that category: aside from his early death, he was most notable for his stick fight with Ted Green in 1969. So it would have been unprecedented for the Canucks to retire his number in 1974, and I can see the reaction being negative.
Now this trend obviously changed, and indeed within 3 years both St. Louis (Bob Gassoff) and Philadelphia (Barry Ashbee) had retired numbers for players who died suddenly. But both the Blues and the Flyers were respectable franchises, and had at least made the Finals by that point; the Canucks had two playoff appearances by 1977, with a solitary win. That they had one of the worst stretches in league history throughout the 1980s (1982 Finals run aside), didn't help with that. So again, if they tried to retire a number I imagine it would not have looked good.
But in 1991 the Canucks did retire a number, #12, for long-time captain Stan Smyl. By this time jersey retirements had come into vogue, and while Smyl was clearly never going to make the Hall of Fame, he was a Canucks legend, and I guess after two decades with nothing to show for it, the team wanted to put something into the rafters of the old Pacific Coliseum. That doesn't excuse why they didn't decide to make Maki's number official, but I would imagine that at that point it was clear the number was off limits (much like #21 in Pittsburgh for Michel Briere, who died in 1971 but only had his number retired in 2001).
That all said, if it was well-known in team management, why did no one say anything to Messier? That's easy enough to explain away: aside from being Messier, who had his reputation behind him and a legacy with one number, the team had been sold recently: while the Griffiths family owned 100% of the team until 1995, they sold 50% that year to John McCaw, a reclusive Seattle billionaire, and the rest of the team in 1997. I can't speak for the dates of the sale, but it lines up enough to suggest new management either didn't know, or didn't care, and felt that it would be fine. Obviously that wasn't the case.
I'll conclude by noting that even after the uproar, it's interesting to see that even after Messier left in 2001, and McCaw exited in 2006, that the team has never officially retired #11 for Maki. It remains off-limits though, and seems to have been joined by #28, which has not been worn since Luc Bourdon died in 2008, and possibly by #37 for Rick Rypien (who died in 2011; though that number had only been used twice before in team history).
