Young Avengers: the Children's Crusade 7 is out. We finally learn the truth behind Wanda's madness in Disassembled. Basically, after losing her children, Wanda went to Doom for help, and together they cast a spell that wound up giving her almost limitless power but driving her crazy.
I'm not sure how I feel about this retcon. On the one hand, Wanda's insanity wasn't the result of an innate character flaw. On the other hand, Wanda was an idiot for going to Doom instead of Strange, Clea, Voodoo, etc.
I wonder when Wanda went to Doom since he was in Hell for several months preceding Disassembled.
At the end of the story, Doom becomes omnipotent and has healed his face. I wonder if this was intended as a tribute to Secret Wars 10.
As far as I can tell Bendis picked his philosophy up "off the street" so that he's by default postmodern. There is therefore no "truth" inside the story about what Wanda's powers exactly are and what has gone wrong. In particular, the characters in Avengers Disassembled do not understand Wanda's powers and therefore are never able to control them, which is why outbursts such as Dr. Strange's "There is no such thing as Chaos Magic!" are completely appropriate to the story.
To have a later story add some extra detail to why Wanda's powers were at a certain level is completely consistent with postmodernism where no one has a complete picture, no one knows the complete "truth," because truth, history etc. are themselves social constructs.
I have the impression since day one of Bendis' reign on Avengers but don't have an exact interview to quote that Bendis has always asserted that Wanda went crazy due to the nature and level of her powers that innately would confuse anyone about the difference between reality and imagination. Bendis shows the same insanity occurring to the Molecule Man in his Dark Avengers run.