Why?


I think it's because at this point in the story, the Dark One no longer needs the Forsaken, so It's having a grand old time devising punishments and obscure reasons for their failure. The Dark One needed a mouthpiece, and various Forsaken most noteably Ishamael volunteered for that. Now The Dark One needs hands and a body, and It's provided Itself with that via Shaidar Haran. When everyone can hear the Dark One in the way the Forsaken can at the Bore, It won't need human servants anymore to deliver It's message.