those two being about the only good reasons to use a 'chute in a powered light aeroplane.
The main reason I wear one is because I plan to get out of the airplane at some point before it lands. Let's face it, freefall is fun.
Slowing somewhat before landing, after freefall, is a really good idea.
One generally doesn't need a parachute in an airplane because one is wearing something better: an airplane.
Many who wear parachutes, either for gliders, sailplanes, or aerobatics, have never actually used a parachute, and this is peculiar.