Hot take: The burning of Teldrassil as depicted in Warbringers and the War of Thorns event was the greatest lore experience ever in WoW and was Sylvanas’s apotheosis. The cinematic Saurfang storyline that followed was also amazing.
What was so disappointing was giving Sylvanas inexplicably calculated reasons for the genocidal deed rather than leaving it as an impulsive act of spite as it was originally depicted. In a similar vein to the op, I’ve written my own fan-fiction concerning the direction I would have preferred they’d taken and about my disappointment with the one chosen: Classic - BFA Era Stories: Oh, the places they'll go