Take a street like melrose ave. It's filled with pretty well leased, single story commercial real estate abutting low rise apartments and homes. Walkable? Sure, if you manage to snag one of the limited available leases in a 15 mins walk. Replace those commercial parcels on melrose with 5 over 1s, and there is no net loss here. The same commercial square footage is available, sometimes more if the the building extends further into the lot versus if the old building had a small surface parking lot in the rear, sometimes a lot more if more than 1 story is set to be commercial space. Not to mention the apartment stock swells up, supporting a larger customer base for these businesses when these apartments are inevitably leased out before long.

NIMBYs in this city bemoaned old Amoeba records loosing its "historic" low rise commercial building. But Amoeba just moved into one of these mixed used developments a few blocks away closer to the metro station, got more square footage out of the deal, and sold the old property for a lot of money. The city changes and it isn't a bad thing, in fact its typically a good thing that it changes as this keeps rents closer to the actual wages seen.