Nefarian, Onyxia and Baron Sablemane are offspring of Deathwing, true enough, but where was DW himself? Absent..
Azurgos in Azshara.. Yeah, he's a blue dragon... But it's NOT Malygos..
4 green dragon world bosses..... No way, you can claim any of them was Ysera..
All in all, the Aspects presence was nowhere to be found, until we killed Malygos, and then completely ignored until we quested in Cataclysm...