The reason the nibs are there is because of Gibson's production process.
They fret the fingerboard BEFORE they apply the binding. Then they remove the excess binding material, which leaves the nibs at the ends of the frets. These act as a transitional area smoothing the frets into the binding.
Everyone else installes the frets AFTER the binding is applied. The ends of the frets are then dressed providing the transitional area. This is also the way 99% of the re-frets are also done which caused the nibs to go bye-bye.
I think the reason some like to retain the nibs, is because it retains more of the originally of the guitar. Might be a consideration on a highly collectable Gibson.
Hope this explains it.
Hamer has the nibs on their binding as well. I think it looks cool, feels nice, and doesn't affect playability adversely. However, if I ever need to get a refret on my Hamers with binding, there's no way I'm keeping the nibs (not worth the cost to me).