Well, I'm not too up on the history of the 29er, but I do know that they got a solid foothold with riders in the US long before Canadians started getting into them. Part of that slower adoption may have been rooted in the Canadian bike industry, which tends to be centered around the Vancouver North Shore scene and Whistler (think All-Mtn.,, DH and Trail bikes). I can imagine product developers for, say, Norco, Rocky, Brodie, etc., who are all headquartered there, looking southward at 29ers and then swiveling their heads to look at the trails out their back door, and saying "Nope. Not going to work here." That attitude may have then been transferred to the dealer networks through local reps across the rest of the country. Who knows.....that's just conjecture.
Also, 29ers do have some big challenges that 650bs don't have. It's just easier to build good bikes for 650b wheels.
Agreed. That's why I think this is a really great development. Looking forward 5 or 10 years, I can see 650 bikes supplanting 26ers almost entirely, and pulling 29er riders into the fold as well, who are looking for a more rugged frame/wheel or better handling. It may well become the new standard, much like 26" has been since the 80's.