cause he seems pretty unbeatable
His fire weakness doesn't seem to be as crippling. Not even sure if it still exists.
His telepathy is very powerful. He can seemingly listen to everyone on earth and shows up whenever someone thinks about him or talks about him. He even appeared on Oa in the Green Lantern Corps to help the Green Lanterns. Than erased there memories.
Holds his own against the Justice League Big 7.
Justice League #20 Martian Manhunter takes Despero on one on one and owns him. He matches him physically and than breaks his mind with his psychic powers