You cant dead stick a cessna in an urban environment, and current ballistic parachutes aren't that heavy.
https://aviation.stackexchange.com/questions/24946/what-is-t...
https://aviation.stackexchange.com/questions/24946/what-is-t...
Except a ballistic parachute does absolutely nothing for you in the scenario where > 90% of accidents happen: take off and landing. Even the most advanced BRS systems on Cirrus planes require 1000 feet AGL. There's simply no getting around the basic physics of this problem.
With a light plane, you can do a lot with a dead stick. They have remarkably generous glide slopes (nearish to a mile horizontal travel for every 1,000 vertical feet). Not to mention being inherently stable whether under power or not.