This is not just a Sylvanas simp thread I actually have some deep things I’ve been thinking about. I am just putting the question out there, that why do some villains that have committed horrible atrocities get their due, but not others? For instance…Darth Vader did terrible things, but he gets a redemption. Voldermort did horrible things, but no redemption, trapped in limbo for eternity.
We know that Sylvanas committed suicide after Devos grabbed Arthas at the moment of his death, so why was Arthas worthy of total damnation, but not Garrosh or Kael’thas?
Obviously you could say Frostmourne had something to do with it, as Mourneblade’s are a threat to the Shadowlands itself, but at the point of his death, Arthas was no longer in control of the blade, therefore no longer a threat to the stability of the afterlife. So Shadowlands was already corrupt long before Sylvanas arrived.
The fact is that Sylvanas intentions are to give everyone free choice, she believes from our first breath to our last, our lives are predetermined, and if this is the case, being judged for our actions in the afterlife is a cruel joke.
The fact that needs to be taken into consideration is that after Sylvanas got her revenge against Arthas, she tried to kill herself, as her destiny fulfilled, but she was shown the worst torments, I mean the only morally grey things she did after becoming a Banshee was killing Garithos (that was a racist anyway), and then the Wrathgate incident, while good people died in that incident, the fact is, that action did force the Lich King into retreat. So those are about the only two things that she would be responsible for prior to her suicide. Yet she was condemned to hell anyway…so why are we at all surprised that she did everything she did after that?
Have you ever heard the saying that the most dangerous man is one that feels he has got nothing left to lose?
But here is the truth of the matter. In our reckless actions of imprisoning Sire Denathrius, it’s clear that Sylvanas has remorse for sacrificing people on her team, now someone that feels empathy towards the people on their side in a war cannot possibly be pure evil, as people have been on opposing sides of conflicts and wars for generations but usually teams work together.
In short, because Sylvanas has two good qualities, sympathy to her allies (provided they are not a threat to her like the ones were in The Gathering), and she wants free choice. These are two weaknesses, that good people will prey upon, no different how Vader had that one weakness, love of his family.
This is why Sylvanas redemption from evil is inevitable.
Edited: Hey sorted out this matter with Blizzard, they are fine with this thread everyone, but keep in mind to not take it too seriously, that it’s all fun talking about the story and lore, okay? 
I mean, I do enjoy talking about it to the extent that it does make me think about a lot of deep philosophical issues, but have fun and happy debating!