Board Thread:Lore Discussion/@comment-24583421-20140302161145/@comment-86.134.25.229-20140305223711

I think the way it was explained before makes the most sense:

The Aedra aren't so much as dead, but now literally represent the blood that created them, Anu, a stasis form. That being said, stasis represents inactivity, which they now are, as they have lost a great deal of power. I wouldn't necessarily say they are dead, but their state is now for the most part, inactive, as they cannot physically interact with the world the way Daedra can.

Daedra being the epitome of change, hence coming from  of Sithis, who stems from   Padomay, Anu's opposite, represents change and chaos. It was because of his nature of change, that the Aedra and Daedra were able to be created in the first place. Sithis created Lorkhan to get rid of the Aedra (and Daedra) and return them to the void, in the process Nirn was created, and the Aedra that got involved became static entities.