It's the old Stephen King line. "Sometimes they come back." It's only fitting that Madelyne constantly resurrects. Part Phoenix Fragment. Part Queen Demogoblin. Who knows what truly powerful forces are at work here?
But the others are correct: Next time they bring Maddie back, let's hope it's to get her far, far, far away from the X-universe. Make her an Avenger, a Defender, an Ultimate, whatever. She could join the Squadron Supreme and play Marvel's version of John Constantine of Justice League Dark for all I care. But keep her the hell away from the X-folks. All they know how to do is ruin her.