Players: “Sylvanas burned Teldrassil.”
Blizzard: “Oh, you don’t know who did it yet~ Hold on and see~”
Sylvanas burns Teldrassil.
Players: “Sylvanas is evil.”
Blizzard: “She’s not evil, she’s definitely working towards a greater plan we just don’t know yet.”
Sylvanas is evil.
Occam’s Razor applies to Blizzard story writing in that the simplest answer is the correct one, except they try to cover it with a thin smokescreen to keep people talking about it incessantly.