I think that the utterly horrific past of the Forsaken is what makes a redemption angle so interesting. Would they be able to let Demandred live out the remainder of his life in freedom for having helped to save the world? If the connection between the memories of LTT and Rand were broken, then no one would remember exactly what Demandred had done since it was before the Breaking.
The reason I brought it up is because part of what ultimately made Robert Jordan's books derivative, run-of-the-mill fantasy was the complete shallowness of the characters. The closest we ever got to a real person was Rand because he was slowly going crazy. However, if Jordan had given more characters really difficult decisions, if some heroes became anti-heroes, if some villains actually did something good, he could have breathed life into the tired cliches that he just reworked.
Imagine a Perrin who is having a torrid affair with Berelain, who has to personally execute a good friend from Two Rivers who turns out to have been a spy for the Dark One and wakes up in cold sweats hearing the friend plead for mercy before Perrin's axe comes down in a nightmare that repeats real life over and over. Imagine a Mat who turns paranoid and tortures suspected Darkfriends, even though he's the only person who has a chance of leading the armies of the Light to victory. Imagine a Rand who occasionally kills the people around him because he's just hallucinated. Imagine a Forsaken who wants to break free from the Dark One but is being manipulated because his family keeps getting pulled back into the Pattern by the Dark One and tortured every time he disobeys. A darker, flawed Wheel of Time would have been fascinating and filled with depth. Instead we just got a predictable derivative series that will likely recede into obscurity.
it's fantasy man, making it GoT wouldn't have made it better IMO. Jordan needed to step up the pace and could have shortened the story for certain, but making it dark and oppressing at every angle would have made the story very dull to me. I liked that Mat and Perrin stayed true to their characters despite all the pressure and evil around them. I liked that Nynaeve kept her drive to heal, even when the world seemed to be collapsing around her. I like that Elayne kept her sense of purpose even when she was dealt a crushing blow. Egwene had to execute hundreds of Black Ajah Aes Sedai, but she didn't let that turn her into a totally paranoid dictator who would execute others based on a whim. Those are the triumphs heros are supposed to have.
Given that WoT is the number one best-selling fantasy series of all time I think it's a bit much to think it will "recede into obscurity" because it was derivative and not crushingly dark. More likely it will struggle with relevance due to the legal issues for rights to make TV/Movies etc