Their design philosophy seems to consist of extending the sidewalks, then jamming as many trees, micro-lawns, raised planters and assorted obstacles on those sidewalks as possible. Looking through their projects I can only assume their true goal is to impede the pedestrian's freedom of movement as much as possible, physically corralling them with "green" barriers so they can't interfere with sacred auto traffic.
At the top of their About page, they begin with a Menino Quote: "The car is no longer the king in Boston." If this were actually true we wouldn't be so obsessed with segregating cars and people; nor would the city's zoning code be filled with parking requirements.