Not necessary. The One-Size-Fits-All approach to seatbelts is a problem especially for short/younger people and women, who often don't wear collared shirts and, therefore, the belt rubs on bare skin. There are accessories of alleviate these problems.
Having started flying when I was 20, I became quickly accustomed to wearing my seat belt and feel uncomfortable without it. When flying professionally, we're only required to wear the shoulder harness portion of our 5-point seat belt during taxi, takeoff and landing. Over 90% of pilots release their shoulder harness on climbout. Mostly out of comfort, but also to keep their shirts clean (white shirt, dirty black seat belt straps).
I know of one fatality due to a person not wearing his shoulder harness in an otherwise survivable crash. I also know where a captain was severely injured because he wasn't wearing his shoulder harness per regulations upon landing...which he fucked up and ended in the weeds.
I always wore my full harness unless I couldn't such as leaving to pee, opening the door, etc.