A question about this for someone more informed. It comes up in thread after thread that the city can't impose on aesthetic matters, e.g. they can't tell a developer not to use grey spandrel. But then how on earth can they make a call like this? Utterly baffling.
At a high level, it's complicated; the city can and does say "hey, we really think the development would be improved for reason x if you changed y, and we'd look more positively on the application as a whole if you do it", which is different from mandating or codifying a specific aesthetic guideline.
In this case, the city felt that the 383-esque brick treatment hindered one of the core goals of the design here, which both the architect and the city explained in their presentation. Because this is a long (wide) site, the city asked the architect/developer to come up with a design that "broke up" the facade in a way that made it feel like the building didn't overwhelm the block. The six "boxes", the fact that they are varying widths, and the use of a different colour of brick on each are the main design response to this goal; in the city's opinion, the amount of brick on each box in the first iteration of the design was a barrier to more fully achieving that goal.
Personally, I disagree with that judgment, which is of course subjective; in most cases, my feeling is that flat curtain walls (or mostly flat window walls), even when accented by fins, are much more oppressive and overwhelming than a more variegated and tactile material.
But that difference of opinion is a pretty good illustration of why aesthetics are difficult to create guidelines for; in this case, I agree with the goal that the city and proponent have set out for this design, but I disagree with their sense of the best way to achieve it.