Could someone provide some insight on why organizations want their names plastered on arenas in the first place?
Ooooh, I can!
Essentially things like this are all about brand awareness. For Air Canada, every Leafs, Raptors, Wrestling, MMA, event that is had, their brand name gets said to the hundreds of thousands of people watching on TV. The millions of tickets printed have your brand name on it. Your brand name would also come up more in people's general conversations. ("Where's the concert?" Etc)
The idea behind these kind of things is that Air Canada was placed in the heads of everyone so much, that when they go to book a flight, they will naturally recall "Air Canada".
Essentially, if 10% of people decide to book Air Canada, it works itself out.