I love a lot of the creatures we face, skellies are definitely a top but also wolvers with there fuzzy looking coats and cute little sleek movements, I often feel bad about "devastating the native populations" just to get me some money or to wear there body parts for amour or costume, can you imagine of there was a creature that went around tearing up our populations then boasting about how good the remains look wrapped around there bodies?
I like to think they don't die but its more like they are destabilized and have to go to the core to reform.
Basically its because they have been around the core so long and in its energy field that they have bonded to it and they are more like bubbles of mobile energy and when we beat them its more like we pop them and they have to go back to re-inflate, this would explain the purple poof after them not to mention how they keep coming back all the time including the "one of a kinds" like snorbolax, jelly king and the other bosses, also we might be bonding to the core explaining why we have to fill with mist or crystal energy in order to walk around.
Anyways random thoughts of rational on a fictional game.... YAY ME!
I think the monsters, especially spookats, and bosses, are more defeated or stunned than killed.