From my PoV, the Burning of Teldrassil was objectively evil. The Horde followed Sylvanas’ orders (after also happily butchering Ashenvale/Darkshore) to kill thousands of innocents.
That presented a really cool narrative for me to play with on my Night Elf, and I really loved Elegy and A Good War, but I can see why it pushed the Horde into a difficult corner - the morally grey expansion angle was disproven during the pre-patch.