Legion got cancelled about ten minutes after the Siegel case settled and WB pulled everything that meant they might have to pay the heirs for Superman appearances. About a half hour after that, the same production unit got turned around to make "Batman: The Brave and the Bold" instead. Look it up.
I exaggerate slightly but it all did happen pretty quickly.
There were a few things I liked about Legion S2, notably the setup of the romance of Chuck and Luornu. You don't have to be a pretty perfect body to have a love story. :-D