Any time the question is "why don't we have...", the answer is almost certainly in the trade-off between weight, maintenance cost, fuel cost, & utility. If it weighs a lot, needs maintenance, burns fuel, and will only be useful once a decade, then it just is not productive.
Putting a complex parachute system on a plane will be heavy, meaning fewer passengers, or less fuel or cargo on board. All that extra weight has to be flown around, requiring fuel. They would need regular maintenance checks, which is another cost. And a parachute would only be useful very, very infrequently (on most planes, it would never be used).
So it is just impossible to justify adding new equipment for a once-in-a-lifetime scenario, which can be better managed with good maintenance, good training, and good planning.
This same line of reasoning goes for "why don't more airplanes have rocket thrusters", "why don't planes have anti-missile systems", "why don't planes have airbags", and many other random items.