I've pretty much always loved the WoW cinematics. The Vanilla cinematic still sends chills down my spine, the Burning Crusade one puts ridiculously thick and pleasing nostalgia goggles on me, and the Wrath cinematic will forever be my favorite cinematic for a game of all time.
Some links to them:
https://www.youtube.com/watch?v=vlVSJ0AvZe0
https://www.youtube.com/watch?v=IBHL_-biMrQ
https://www.youtube.com/watch?v=BCr7y4SLhck
In all of these cinematics the focus of the expansion and the story in the expansion were always shown. You watched them and you knew what the game or expansion was going to be about. But recently, I don't think that's been as much the case anymore.
In Mists of Pandaria the cinematic was about finding Pandaria and the inhabitants on it, but in reality the expansion ended up being mostly about the Sha and Garrosh, which weren't in the cinematic.
In Warlords of Draenor the cinematic was about Grom Hellscream not drinking the blood of Mannoroth and Garrosh being there back in time with them, and it shows them basically building up the Iron Horde. Now I will admit I didn't actually pay that much attention to the story in WoD, so I'm not 100% sure if the cinematic really matches what the story will be like in the expansion. But from watching the cinematic and having played the game they don't really seem to match that well in my opinion, at least not as well as Vanilla, BC, and Wrath did for what actually ended up happening in those expansions.
And now, the Legion cinematic. Watching it I have absolutely no idea what this expansion is going to be about story wise. We fight the Burning Legion, okay, I get that. But Varian and Sylvannas are teaming up as allies, and that's pretty much about it. I have no idea where else it is going to go story wise outside of that just from watching the cinematic, whereas in previous cinematics it was definitely a lot more obvious.
By this point you've read all that I've typed out and you're probably saying "Why do you care so much about what the cinematic is like? It's not like it has any affect on what the game will be like". And I get that (and for the record, I think it should have affect on what the game will be like, like a preview on what the actual story of the expansion will be), but for many people I think whenever there's a new expansion coming out and Blizzard releases a cinematic, lots of people get really hype about what is to come. And I'm having a hard time getting hype about "what is to come" in Legion because frankly, I just have no idea the direction they're going to go in with this expansion at all outside of the fact that we're going to be fighting the Burning Legion. Other than that, I honestly have no idea. From the cinematic alone, I have absolutely no idea what this expansion is about outside of the Burning Legion.
So, I don't know if Blizzard will even ever read this, but please in the future keep your cinematics more like a preview or a small window into what the expansion may hold. You don't have to give everything away, but at least have it stick to the theme of the expansion. I'm tired of seeing a great little cinematic preview of an expansion and getting excited about it, and then halfway through the expansion the game's story has completely changed and the expansion is completely about something different now and I have no idea what is going on anymore story wise.