There was a post recently, titled something like "How do you feel in your nappies "
It is not so much that nappies are too comfortable, but that they feel "safe", or perhaps more accurately, the separating waterproof barrier between the world and the wearer, makes the wearer, whether geriatric, ABDL or aware toddler, "Feel safe" even when the nappy is uncomfortably bulging, clumped or stinky.