It worked with Ignatieff, but I think there's a few major differences here.
First and most importantly, Ignatieff looked like a sentient fence post in pain when he spoke. There was never any charm or humanity there. That was always the big concern with Carney, we were worried that he was all economy wonk, no personality. He's beaten those allegations for the most part, even his awkwardness with keeping the political talking points straight has a bit of "awww shucks, I'm new at this" charm to him. With Ignatieff, everything felt like what sitting at one of his lectures must have been like. If he was charming, he might have beaten Harper.
Second, Ignatieff himself went out of his way in books he wrote to refer to himself as "cosmopolitan" and more or less post national. He didn't necessarily run from his Canadian heritage but dude spent his entire professional life outside of the country. Basically, he was Canadian by birth, but pretty clearly not by choice. If Carney didn't have his BoC run on his resume, this same criticism might stick but he did, so it doesn't. His fantastic work as head of the BoC is why Canadians know who he is, and want him.