Imagine instead that parachutes were integrated into seats and opened automatically. Each seat would be an ejection seat and passengers would be strapped to them with something more reliable than today's 2 point belts (like pilots of the fighter planes). You could also fit some limited oxygen supply system into the seat in case of high altitude ejection. Of course blowing off the plane's roof and mass ejection sequence could be only initiated by pilots.
It really doesn’t make sense having parachutes on your average commercial flight. Most times, the plane is over open ocean or a vast mountain range or something. What good does it do to jump?
