Speaking for myself, I absolutely despise what has become of Sylvanas and I frankly believe her inclusion not only in the story but as essentially the main character of the game for the past 2 expansions is dragging the entire franchise down.
That said, I really, really liked her from Frozen Throne until Wrath. The no-nonsense, do whatever it takes, ruthless to a fault, committed to her plan, third party villain. They had a great arc with her. While being relatable, you saw that she was heading down a path with no good ending. It was self-destructive and ending it with her accomplishing her goal but finding even that empty and thus killing herself upon the spikes of Icecrown was tragic and just beautiful honestly. Some stories have a sad or bad ending. And that’s okay.
But then Blizzard kept her around because she’s popular and ever since Cataclysm she’s just been a huge mess. She’s waffled back and forth between Villain, anti-hero, champion of the Horde (The most absurd version of her) back to villain, all the meanwhile doing things any other character would have been annihilated for twenty times over.
That is what ruined Sylvanas. And you can’t really salvage her, sadly. Even if Tyrande showed up and killed her, burned her with Elune’s fury, and spat on her ashes, that still wouldn’t be enough to justify all the things she’s done. She’s become such a one-note meme of her original self that there’s no coming back from it. And no matter what Blizzard does, some significant chunk of players will be forever upset at it.
It’s a problem they’ve created for themselves and frankly I don’t feel bad for them getting the heat about that that they are now.
(Now obviously I’m not excusing the psychopaths harassing and threatening developers, that’s terrible and embarrassing and just pathetic).
Having a finality to a character’s storyline is just as important as the arc you tell to get there. Stick to a beginning, middle, and end and deliver on it well and people will remember it forever, even if the character is no longer in the story. Blizzard’s problem is that they see characters solely as advertising fodder and so people very, very rarely die.
I can’t even think of what the largest death World of Warcraft has had. I guess the Lich King? And then probably Varian? Everyone of any kind of import stays alive and it kind of saps all the tension out of a story.
I don’t know how much these official forums support talking about other MMORPGs, so I’ll be brief. But FF14’s first expansion, Heavensward, has a major character death after a satisfying arc and the fact that they stuck to their guns and just kept them dead made the death SO much more impactful. So much so that they are STILL referencing it 5 years and 3 expansions later and players still get the feels for it.
Warcraft could have that if the developers saw the characters as more than just marketing tools to sell the game and as actual characters in a story.