What 'mistakes of another era' are you referring to? The time when Bloor was all stately homes for the wealthy elite? Should we be going back to that era?
One of the things that I find interesting about the Annex, in particular the mid-rise apartments which dot its landscape, is how much of the existing nineteenth centry fabric actually remains
intact. So if your caps-lock-diatribe about the 'mistakes of the past' is centered upon the false notion that houses were being cleared out wholesale, not only are you wrong about that time, you're wrong about this one too. Most of the mid-century buildings around here only removed one or two houses. Some of the larger slabs took three or four. 20 Prince Arthur is by-far the largest at seven, but only because it included a generous park for tenants to the west.
What's also remarkable about the Annex is how it's got to be one of the most diverse neighbourhoods in a city and country full of them. Where else do you have university-age renters a couple of hundred feet from grocery billionaires next to literary giants? What a great city, what great (former and, in its own time, not without its own fights) planning.
I actually started a thread about this exact thing last week. You might find it interesting:
https://twitter.com/ProjectEND/status/903278492103704578
Neighbourhood destruction? Not that I can see. 'Mistakes of another era'? Unfounded and without evidence. But why don't we use your list:
Good planning? I'd say so.
Appropriate design? Not my cup of tea, and as an aside, unbuildable as shown and at our city's price point, but if that's what they want to do...
Continuity of a neighbourhood streetscape? Well yes, actually. Replacing a single building with something taller is kinda what the latter half of the last century was about in this neighbourhood.
A rookie developer who grossly overpaid for a site? I know what they paid for this site, do you?