+1 to cccorlew and DigitalGee. I'm not sure I can explain it either.

I rode with bike shorts years ago, but when I returned as a 50+ I was perfectly comfortable up to a couple of hours with normal shorts. HOWEVER, when I did switch back I got both bibs and bike shorts. Now, I'll ride the trainer with the bike shorts but if I'm going outside I wear the bibs.

You probably won't miss them if you never get them, but trust us, the bibs are more comfortable.