That's the one!
Yes, I like how this was designed. The metatarsal on the hand allows the base of the thumb to fold over the hand palm, making some poses look more natural, causing less stress on the mesh. Here again, it was done with a ghost bone to avoid adding a new group to gloves, which was very thoughtful. It's there, but it's optional. I remember being hired for a private commission to allow Genesis feet to pose like this using morphs.
I know other people want 3D feet to be able to bend like this, so perhaps all figures should have this extra ghost bone on the hands and feet. It's the kind of thing that after we get used to it, it makes us wonder why other figures don't have it.