Denny Duquette (Jeffrey Dean Morgan) was a beloved "Grey's Anatomy" character. Not anymore. Not only did "Grey's Anatomy" wear out his welcome by dragging him back multiple times last season as a hallucination courtesy of Izzie's cancer-ridden mind, the show utterly desecrated his memory by having Izzie deciding that she wasn't seeing him out of love, but out of that's who she associates death with.
All this managed to do was use up viewers' patience. Sorry, folks, if you kill someone off they need to stay dead.