/\Though you make a few good points, in the end Bloor/Dundas needs this sort of density. It is a major connection for the TTC (Streetcar, Bus, Subway) and GO (Trains) and is located in an area with plenty of parking lots, empty lots and old industrial sites which could be rehabilitated and densified.
With regards to the Crossways Towers, I love them. Not necessarily because of the architecture (which I also like), but because they act like a sort of landmark or point of reference for the west side of the city. It can be seen from Bay/Bloor (close to where I go to school) and Jane and Bloor (close to where I live) and is pretty much the half-way-point between those two spots. As such, whether taking the subway (D/W Stn), riding a bike or driving, it lets me know exactly how far I still have to go.
Additional buildings would bring new people to the neighborhood and with designs like TAS' "Giraffe" (apparently that's the name according to TAS' website), bold, new architecture as well. The street level looks bland because this is just a relatively monochromatic preliminary render. The people are black and white, the building is shaded but is also basically black and white. In the end, this is an evocative design which enters an interesting conversation with the all brick Crossways.
Build it.