DigitalSciGuy, thanks, you put it much better than I did. My whole point was that there are ways to disperse residential density out from downtown and into the neighborhoods without plopping down some 30 story towers on your (and my) grandparents' bucolic Hyde Park residential street. 95% of the existing single family built environment doesn't need to change.
Per curcuas' point above, just start upzoning the properties which immediately abut major throughways near transit. 1-2 story building lining these streets doesn't make sense and majorly inhibits the city's capacity to add more residents.
And while I agree this won't suddenly reconfigure commuting patterns or produce huge amounts of new local jobs, there should still be a net-positive in local employment if done properly: in Tokyo, the ground floor of each of these 8-15 story midrise spine buildings is retail. Restaurants, drug stores, supermarkets, green grocers, stationary stores, convenience stores, bank branches, whatever.
We will never hit housing goals if we bank on small-scale, piecemeal development in Dorchester coupled with the few residential towers NIMBYs don't kill off downtown, ala Longfellow Place.