Parachutes would barely save any lives.

First, commercial air travel is incredibly safe.

Second, parachuting requires extensive training which a negligible number of passengers have. It's not like you just jump out of a plane and it works automatically. Not to mention dealing with cold, oxygen deprivation, landing in the middle of the ocean, etc.

Third, it's going to take at least a half hour for everyone to put parachutes on and jump out in an orderly fashion. How many aviation accidents have had a half hour of extra time where they already knew they would fatally crash?