The natural state of Centaurworld is irrelevant, silly, & magical. The selfishness of one man dividing the two worlds brought so much endless trauma & suffering that deep perversions like the Whaletaur Shaman taking on others' emotional pain by offering magical assisted suicide becomes commonplace.
Centaurworld was an amazing experience. It started out like a simple isekai -- one world at war, one world very childlike. Then you learn how traumatized Centaurworld was, watch the body horror take Horse, and how much depression is happening there.
Both worlds were suffering, it's just that the magical forces of Centaurworld makes the trauma just underneath the surface so much harder to see. And since the rift has the effect of sharing attributes between the worlds and sealing it exaggerates their natural attributes, it's even more hidden.