The focus on affordability in new housing is, I think, a glaring example of short-term thinking. I mean sure, those sparkling new condos that somehow managed to squeak by the municipal approval process (the length and cost of which are no small part of why they cost so much) may be out of reach for most people, especially newcomers. But with time—or even sooner after, say, I don't know, a recession?—what was once luxury condos may become decidedly middle-class housing.
Building luxury downtown apartments and saying that they'll making housing more affordable for everyone really feels like trickle down housing to me, ESPECIALLY when combined with an argument that the economics will take care of themselves.
NYC where I live is chock-full of housing developments which began either as affordable (https://en.m.wikipedia.org/wiki/MacDougal–Sullivan_Gardens_H...) or luxury (https://en.m.wikipedia.org/wiki/The_Ansonia) and that, with the vicissitudes of economic cycles and time, flipped their tax brackets (and sometimes more than once).
The point is, supply is supply and, given enough time, the economics will take care of themselves.