Delixe: I mentioned them and you know. They might be WRONG. The Inquisition will not take the risk. That's the in-story reason.
As chris.frukacz points out the real reason is that they want to keep selling Warhammer 40,000 and they won't do that by advancing the story. Ynnead and The Star Child will never be born, Cypher will never reach Lion El Johnson, Ghazghull will never unite the clans and Eldrad will never be confirmed dead.
So it's all about greed? Nice.
chris.frukacz: That's how it works: tabletop drives everything else. And that is as much as game devs @ GW care about "other W40K fans". If you don't understand, go read fanfic or something that will break lore/fluff.
And tabletop shouldn't have as much of a hold as it does on the universe.......they could change things and still make the fans happy and sell their precious action figures to what amounts mainly to manchildren(the hardline collectors not all tabletop players)
GameRager: I just posted about the star child, and it seems he can't become it while on the throne. Again, they need to disconnect him already if they even want that to happen.
klaymen: Reborn Emperor might be a little bit upset about the Ecclesiarchy (and the E might mot like it either), since his goal was to remove all religions, yet they worship him as a god.
If his will is so strong why doesn't he sense what's going on, flatline himself somehow through his will/magic/etc and rebirth himself?
Some of his storyline makes him seem all powerful, while other parts make him sound like a senile will/mind/old man.