To be serious for a moment, I find them very comfortable.
I was already using the term VGN so was delighted to see it on here and couldn't resist the name change.
I've never liked PJs which ride up and I don't like the feeling of a waistband at night. I found it so difficult to find cotton jersey nighties that weren't twee or garish. T-shirts are too short. Man-made fibres are too sweaty. I get cold shoulders at night so wanted a sleeve. But menopause has been screwing around with my temperature control for well over a decade now so I also wanted to be able to stick my legs out from under the covers to cool off. And be covered up getting up in the night because menopause has also been messing around with my sleep. It's cool in summer and warm in winter.
The VGN ticks so many boxes.