Man, those few pages of Uncanny Avengers #1 are really burned into your brain.
Ironically, Brian Bendis of all people provided a different explanation in his All New X-Men/Uncanny Avengers crossover, where Teen Jean says she couldn't help looking into Wanda's head and seeing M-Day there because it weighs so heavily on Wanda's mind, like it's all she ever thinks about.
Honestly Bendis's handling of the whole issue in that story was pretty good. The original X-Men are outraged that Wanda is an Avenger after what she did, and this is used not to demonize Wanda but to reveal to them what hypocrites the adults are for condemning Scott Summers. Wanda replies that she didn't "consciously" do what she did but what exactly happened or whose fault it was is left vague. Wanda haters get to enjoy seeing her called out, Wanda fans get to enjoy seeing her zap Jean into the ground (as she always does in every continuity). I honestly think that despite Bendis being the one who wrecked Wanda he'd have done a pretty good job of using her after she came back.