The REAL REASON why the Primus was not in the ending cinematic...

[Soon-TM]

people say that the Jailer was not properly fleshed out as a character. Maybe that's because he wasn't meant to be? What if the actual villains of SL were the four leaders of their realms; Winter Queen, the Archon, the Primus and Sire Denathrius. The Jailer discovered they planned to do something horrible and tried to stop them - first by taking their sigils and when that failed he concocted a plot to starve them of anima instead. The Primus discovered his plan and went to stop him but was captured, which also put a wrench in their plans as they needed the sigils and had no clue where his was. We kill him in 9.1, discover his backstory afterward and then stop the others.

Frankly this would have been a much more compelling story than... Whatever thing we got.

[deftualjuice]

The Primus was in the ending cinematic, what are you talking about.

[Powerogue]

That's your fan fiction speaking. The real reason is that all three other covenant leaders had a model made for them to be used in other cinematics, the primus didn't. They're not about to create a model for their cinematic for like 2 seconds of dialogue.

This is also the reason why expansions tend to focus their cinematics on a relatively small cast of characters, like how many this expansion were Jailer, Sylvanas, Anduin.

[Ophenia]

And, as others pointed out, the only reason the Primus isn't in the cinematic is because they didn't want to make a fully animated model for such throw-away pointless cinematic.

They have created numerous high-quality CGI models for 2-seconds of appearance elsewhere, surely it was not that much of a burden to add the Primus as Cinematic-quality (not even top-notch quality, just the random shitty WoW-cinematic-quality).