Well, meditation isn't so strange. But I just realized why Illidan may have made the right decision by refusing Xe'ra. The Lightforged are blind to half of reality's nature. Turalyon was unable to see Argus's visions because of that. ...because they are not free...
If Illidan had allowed himself to be Lightforged, he'd have blinded himself to certain possibilities. He'd be unable to properly perceive those futures which were born from darkness.