First of all, if this happens at the very end of the movie as it seems, and characterization is good, we should feel for him, I mean, there are standalone, serious movies where important characters die and you feel bad, Titanic for example, you didn't need 4 movies to root for Jack, so stop with the "Marvel way of the highway" bullshit.It's dumb to even imply/fake his death. Like yea we all know he's coming back. And while I realize Doomsday exists strictly to kill Superman, there's no weight to it in the second film.
Like imagine Marvel killing Cap in Avengers. It wouldn't work in the slightest. Now they might do it Civil War, which is four movies of knowing Cap, and it works.
Second of all, this movie's characters have the advantage of decades of cultural mindshare.