Neoprene knuckle padding is layered rather than solid, which keeps the glove's profile low enough for grappling exchanges while still absorbing striking impact — solid foam blocks would add bulk without improving protection for the open-finger design.
MMA gyms running combined striking-and-grappling classes are the main buyers, with 4oz used for grappling-focused sparring and 6-7oz preferred for gyms doing heavier striking work.
Leather palms should be conditioned occasionally if gloves see daily use, since dry leather cracks at the finger openings faster than the padding wears out.