I dunno. The 80s cartoon were peak for me (Late 50's by the way). We had Transformers, G.I. Joe, Thundercats, He-Man and the Masters of the Universe,...
It was either seeing reruns of the 90s cartoon or reading a trade of the Dark Phoenix Saga. I have no idea which was first since I was so young, but...
'Why?' Just to see the disappointment on your corn-fed, gee-whiz face, Superman. And because a great dark voice on the edge of nothing spoke to me and said you all had to die. There is no 'Why?'