Yes, we did build great things in the past, when our nation was young(er) and the broader Western world was not yet in decadent cultural/moral decline.
Somewhere along the way, the Canadian cultural character lost its propensity to dare and dream big once our establishment was handed over from generations formed in the hard crucible of late-19th century geopolitical fragility, Depression, and/or the World Wars to generations that had known nothing but postwar-boomer comfort and contentment for their whole lives.
Somewhere along the way, we Torontonians/Canadians decided that the labour and toil of building up our city and nation was "done", and we could sit back, stop aspiring to "more" or "greater", and let things deteriorate.
The classic adage of "good times creating weak men creating hard times..."
I'm not saying that we won't ever be capable of great things again, but one must realize the cyclical nature of societal advancement and regression. Building a truly magnificent structure at East Harbour (or condos not laced with spandrel, or streets that aren't overloaded with frontier-town wooden poles, dangling wires, and cracked asphalt, etc. etc.) isn't simply a matter of "if only we tried harder", "if only we'd gone through a proper design and procurement process". No, the problem is far more upstream than that. We need to become a society and culture that once again has the gumption and courage to think bold, dare, advance, and transcend. That spirit belongs to China and parts of Southeast Asia and the Middle East nowadays. It is decidedly broken in Toronto, Canada as a whole, and a good chunk of the broader West.
I'm not the least bit surprised that East Harbour isn't turning out like the "Union Station of our present age", or something of the calibre of the Harris Water Treatment Plant or both our old and new City Halls. Because the present age is a diminished age here in Canada in which we've lost something so emblematic of the earlier stages in our nation-building journey: ambition.