I think we need to move away from the concession model (plowing the grid roads through ravines/river valleys like they aren't there) and build a road network and communities that work with the natural landscape. That would ameliorate the walkability impact of natural landscapes if we are leaving them as boundaries between communities. And the idea that all the density goes on the arterial is kind of a crazy model we have developed in North America. Arterials are roads designed to optimize for flow, and they serve a role in the urban fabric. A road designed for flow cannot also be a street designed for place-making/community. So, let arterials optimize for flow, and don't put dense housing/uses along it. And have streets and paths for place-making and active transportation, with retail, housing, and commercial uses away from roaring traffic. Our cities are built so completely ass-backward it boggles my mind. Nodes of density should be in the centre of blocks of arterials, focused on major transit stations, and not focused on the intersections of arterials, which are highly unlivable.
Indeed. The habit of placing highrises at the very edge of arterial roads seems to be a product of unhappy compromise. The social change advocates want density and walkability; the locals in SHF don't want to be disturbed; at the end, the former get highrises near transit and the latter get to keep the rest of their block intact.
Big picture, it would be better to have highrises shifted inside the block. Those extra 50 m or 100 m of walking to the street won't make the neighborhood less walkable or less transit-friendly, but will make the inhabitants happier: less noise and more comfort. And the street itself should be lined with a 1-2 m wide green strip on both sides, and then maybe low-rise retail.