I tend to do the same thing with my A format barres.
I don't know why jerry did it, but I find it easier to finger and less stressfull on the wrist when I'n not looking to ornament my chord
I too use my pinky, although my guitar teacher doesn't like it. He says the pinky should be kept free to play other notes if needed. I just love how easy it to play a Barred E-form and drop right down in the same frets to Barred A form esp, the G/C combo for "Bertha". Also the last joint on my pinky has so much more mobility than the ring finger and can bend almost completely backwards so it doesn't cover the high E string the way my ring finger does. It just is so much more comfortable but I practice it the other way as well and am getting the hang of it (sometimes).
**it doesn't cover the high E string the way my ring finger does.**
I also can voice the high e better with the pinky. I also will use the ring finger if I want to use the pinky for a sus4 or 7th etc. It's best to not be married to either I'd say but I mostly use the pinky, undoubtedly the influence of jg.
I'll often barre just the b, g & d stings with my index finger if I'm not concerning myself with voicing the root bass note. Easy to work major scale licks off of that.
Or use just the ring finger for the the above referenced strings and have the index finger poised 2 frets back to barre and work some blues licks.
On top of what everyone else has said, using the pinky just looks cool. I am glad I spent so many years using the pinky b/c now that I am actually studying jazz guitar and attempting to play more jazz (with apologies to Joe Pass, of course) my pinky is as "strong" as my other fingers - which when playing 13th's and the like sure comes in handy.