The Earth's Greatest Hero has fallen...
WHICH IS THE MONSTER THAT EVERY COMIC BOOK TITLE FEARS???
There is a monster even more terrifying and powerful than Doomsday that inflicts fear into the heart of any comic book title...
The Low Sales' Monster!
The four Superman titles selling at that time were suffering low sales, and the editorial team thought that if "nobody" was reading them, then it was better to kill off the character.
This is something hardly new in the business.
The Batman titles, back in the 60's, were suffering low sales too and believe it or not, the campy TV show of Batman saved of the cancellation to the comic book titles. (Just have that in mind, the next time that you may have the unfair need to critizice that TV show. No one can't deny the campiness of the project but without it, you wouldn't have all those cool graphic novels, films, animated series and even characters like Batgirl(Barbara Gordon)).
With Wonder Woman, the Low Sales' Monster was even more unmerciless, since the title was cancelled on the 70s. One of the only three surviving characters of DC Comics after the WWII and witch hunts from the censorship, was just cancelled. Yes, it got back later but that never-ending long run was broken. For a few time but broken nevertheless. A shame doing that to the greatest female super-hero character ever created.
SUPERMAN WILL BE KILL BY WHO???
Obviously many people argue of why creating this "Doomsday" to be the one with the "honor" of killing the Earth's Greatest Hero. To be fair, I think that if the creative teams would choose Lex Luthor, Brainiac or Darkseid, the people would argue just the same, since always there would be fans of the villains not chosen for this "honor" in comic books' history.
I think that "Doomsday" personified, at that moment, the unpredictability of life, the embodiment of the chaos theory. While stories in comic books, novels and films usually have the advantage of a script, where the "coolest" villain with tons of history on his/her shoulders is the one with the "honor" of the "final killing", in life, you can't control who or how you will die, and then, Doomsday showed how any day can be the last day of any character, even Superman.
WHERE THE HECK WERE THE REST OF HEROES???
It's a fair question where the heck were the rest of heroes while Superman was fighting alone against this unstoppable force known as "Doomsday". True, the Justice League of America faced the monster before, but at that moment, that team was harldy seen as the most powerful super-hero team on the planet, but at least they didn't hesitate to battle that monster. But, where was Batman, Wonder Woman, Captain Marvel (Shazam) and the others?
Well, obviously it was an editorial decision, but thinking inside of the logic of the wonderful world of comic books, well, it just wasn't their battle. Easily can be said that all of them were busy attending their own crisis, but at the end, Doomsday was a job for Superman, simple as that, not matter the deadly consequences of that. Help is always grateful but there are moments in life that a person should face his/her monsters all alone.