There's no way Toronto will get a 380 meter building in our lifetime with the current planning guidelines. People with find a way to complain till the end of the earth before something like that will ever be built. The Mirivsh building broke the precedent but if it was proposed at even 330 meters, the city wouldnt even blink an eye before rejecting it.
The sad thing is that taller buildings would benefit the city a lot more then a bunch of 150-200 meter buildings, densely packed together with little variation in height.
Well, yes, any municipality benefits from high density if it means you are consolidating future investments in both public infrastructure and public services. Liveability in and amongst high-density real estate, though, can become increasingly questionable without adequate transit options, green space and streetscaping.
It is not just NIMBYs who fight against tall towers; developers and governments do too. These large projects eat up more of the available market, possibly meaning less for other enterprises. For government, a lot of additional density often means infrastructure upgrades they may not be immediately prepared for (unfortunately). From an economic perspective, developments of a more modest degree tend to be more easily absorbed by the market, calming fears from investors.
If every new tower that went up in Toronto was a supertall it is more likely that a sudden price correction would occur, stunting new projects from happening. We should be thankful for the historic progress made in Toronto's downtown -- even if some descriptions of it reduce the meaning to "a bunch" of 150-200 metre buildings. Has this been the largest and longest real estate boom in Canadian or North American (or Western) history?
In terms of The One, I'm liking the new rendering, and I wouldn't be overly upset about a slight height reduction.