Why is Kingdom Come so popular?

So I've been buying a bunch of Superman comics lately and one I always see listed as a must read Superman comic is Kingdom Come. Having just finished it I just have to say that I really don't get it. The premise is interesting, retired Justice League members coming out of retirement to deal with an out of control new generation of heroes is cool but the religious overtones, everyone acting vaguely out of character, and art style really turned me off. I also found it really weird just how much this comic felt like a testbed for Injustice, a comic most Superman fans seem to hate. Lois is murdered by the Joker, Superman loses his idealism, Wonder Woman starts being a bad influence on him, accusations of facisms, a prison camp for superheroes who don't "get with the program", and at least in the beginning his animosity with Batman are all things in common with Injustice Supes. I found the ending especially to be rather lackluster. So really what is it that makes this comic so memorable and such a mainstay of Superman recommendations???