Soft padding is more necessary for us old bones. If you think about it, a child walking on snow does not leave as deep of footprints as an adult. Or as deep an indent on a mattress. Kids are more comfortable sitting on hard floors than adults are.
A lot of newborn stuff isn't as soft as you would expect. The thing is, if it's too soft, it could compress and your baby would slip out in the case of an accident. Also, if it's too soft, your baby runs the risk of asphyxiation if it ends up covering baby's face for any reason.