I agree with Sylvanas. About a great many things.
The Alliance’s treachery and rampant aggression prove Sylvanas right, even if she does not utter a word. She may respond to the Alliance a bit heavy handedly… but they do not seem to learn any other way.
I also agree with Sylvanas that the “gods” themselves must be brought to heel.
Odyn forced Helya to serve him as a Valkyr and forced the Vrykul to become his servants in their after lives - even though they rejected the notion.
Bwonsamdi serves a boss. That boss wanted Voljin’s soul. He also seems to want a Warchief’s soul. When he asks Talanji for Sylvanas’s head in order to free her of the deal Rastakhan made, Bwonsamdi says he has wanted a Warchief’s soul for a long time.
Someone is screwing with Voljin and Sylvanas.
The Lich King has the power to cause chaos and serves his own ends. He needs to be watched. Especially if he can be replaced.
With all this in mind, I think Sylvanas has the right idea, and is very forward-looking. We can claim our own after lives, free of these “gods”. I do not know what she has planned - but I know the current crop of Afterlife Entities needs to be removed by force, and replaced.
I can see a motivation in all that.
But Azshara is not even pretending to have a greater good beyond herself. In her mind, she is the best, and the greatest good is to serve her. She seems capable and cunning - but she does not motivate me.