Okay so each of the aspects were given their duties and their powers by Titans.
Nozdormu - Aman'thul
Alexstrasza and Ysera - Eonar
Malygos - Norgannon
Neltharion (Deathwing) - Khaz'goroth
I think that it's possible that there is a lot going on between the titans, trying to fend off the evils of the universe, mainly Sargeras and his Burning Legion. Maybe the titans said that once they fulfilled their purpose they were to give the powers bestowed upon them back so that the titans can stand stronger against Sargeras and other evils? What do you guys think?