Actually, I've suggested before that if the Union Station trainshed were moved elsewhere (say, the Portlands), it might make a nifty and even "acclaimed" public facility...
But we're not talking about that--we're talking about the "bridge" that once (until 1954, I believe) connected the St. Lawrence N + S Markets. Which, unlike the Union sheds, didn't just serve paying passengers--it was an in-your-face urban landmark.
Now, imagine if it (and presumably the original N market as well) had survived into the mid-70s--almost certainly, I'd imagine, it would have been restored together with S St. Lawrence. And it'd be beloved today (of course, restored and spiffed-up, it wouldn't seem anything as harsh and ungainly as it did in that ancient linked image--but that's what old B&W photographs can do).
Conversely, had UT existed 30 years ago, I'd imagine a (maybe not just) andrepalladioesque sentiment against keeping/restoring even S St Lawrence--y'know, just a big gloomy barn in public-works Edwardian, with an undistinguished clumsy chunk of the Old Old City Hall in the middle of it all; what's the point, except to appease the "hysterical types"?
Heck, even now, one might maybe claim such sentiment to be "vindicated", i.e. that the restoration was a typical Toronto "failure of imagination" as opposed to something bold and new and spectacular, and the Market Gallery is a taxpayer-drain white elephant, bla bla bla...