You forgot they are good exercise - or at least a little more movement than just sitting and stepping off and on the pedal.
I like sewing with it because mine did belong to a great-great aunt. Even though I never met her, I heard wonderful stories about her and believe she would be happy that her machine is still in the family and getting used from time to time.
You are right, no one asks to borrow them - but I did make my sister sit down and sew with it. Told her she needed the experience. And ya know, she liked it, so bought one of her own.
And they are just plain fun to use - anyway, I think so.