Multiple monster models for the Unburied does seem useless since you won't be encountering a cluster of these.
However, since this big guy will be one of the tougher monster to take out, it would look cool if you had maybe three different models for it. I suggest maybe a huge gash in it's stomache with guts and such hanging out. There must be gore in the game! (Like the siege beast biting off the barbarians head)
But, when you say "What does it matter if the monsters will be lying on the floor dead in the matter of seconds anyways", I definately agree 110%.