We live in Belgrano in a 24-hour doorman building and never even double-lock the doors when we leave. Now, that being said, my wife would refuse to live in a non-doorman building or a single-family house anywhere in the city. There have been far too many stories of home robberies, both when people were away as well as when they were home. I know of one expat couple who left Buenos Aires after being held at gunpoint in their house in Palermo.
It definitely makes sense to take precautions here, but the level of those precautions depends a lot on your particular situation.