And the answer is "No!" It's been a while since we've seen a game writing team face-plant so spectacularly. Not since Mass Effect 3, in fact.
In my opinion, the problem is the writers' use of emotion. Emotion must be anchored in reason. If emotion is divorced from reason, the character is irrational. And no one likes following irrational leaders. It's especially bad for Sylvanas, who's basic character is the cool, calculating, ruthless archetype. A night elf talks smack to Sylvanas, she gets mad, and burns the tree in a fit of anger? That's so far out of character that it's just senseless.
I'm not objecting to Sylvanas burning the tree, by the way. It was almost totally what I hoped for. (A pity the Horde did not have a quest to light the torches and fire the catapults!) If only Sylvanas had said something to the night elf like:
I am not wasting a Horde army in a pointless occupation. Nor will I watch them be bled by your sentinel "resistance". Burn the tree.That sort of attitude would have been totally in line with the existing characterization of Sylvanas, and lead to the same result.
Other than the cinematic, the conclusion to the War of Thorns was short but decent. The final Alliance quest, where you try to save as many night elves as possible before being overcome by the fire, was excellent. A great use of standard quest mechanics to drive home the point.