I'm genuinely surprised at how few people showed up to speak against it... wouldn't be surprised if it's a summer time thing...
In terms of the number of Councillors voting for it... call me cynical, but it wouldn't have anything to do with the fact that Truman is local and the guy who runs it loves to donate to municipal campaigns and Rio Can is a REIT with a head office across the country and probably never donates to municipal campaigns.... right?
I'd be inclined to say the biggest reason Glenmore Landing was denied is because of the heavy moneyed interest against the project — billboards, websites, colour-coordinated t-shirts, fake CGI out-of-proportion renderings —
they were extremely motivated and had money to boot. Riocan, while having money, was not motivated to actually put up a fight. The wealthy retired residents of the area couldn't stand to see a few towers in their backyard and had nothing better to do with their time than stand in front of council and complain about birds flying into buildings and dog poop on the sidewalk, all to prevent housing and amenities from being built.
Unfortunately, this council took the bait, even though the Glenmore Landing site is a glaringly obvious spot to put that kind of density.
Now the NIMBY's are emboldened, and developers are disinclined to propose projects in certain areas of the City with those kinds of highly-motivated, wealthy, NIMBY residents.* I expect this, in the future, to play out in a sort of disproportionate fashion, with some neighbourhoods in the city becoming lively, walkable, dense, mixed-use areas, and some slowly rotting away, akin to those of Detroit. Marda loop being an example of the former, where, as
@MJC said, "The lid is off for density."
Calgary has always been a city of extremes, and it seems we are only marching further down that path.
* = Some areas of the city are wealthy but not NIMBY (younger homeowners, newer areas that are more accepting of development, i.e. West Springs), and some areas are NIMBY, but don't have enough wealth to fight development (gentrification).