In the What-If, however, Doctor Doom detects The Beyonder's survival and doesn't fall for his trickery. The heroes are not revived and Doom is free to master his new powers and return to Earth.
He does, and pwns heavily. He is opposed first by Tony Stark and Doctor Strange. He simply adjusts Tony's Blood Alcohol Content to make him permanently drunk (bypassing the 'bottle' part of “Demon in the Bottle”) and though Doctor Strange has spent time in a hyperbolic time chamber preparing new spells for the battle, Doom simply Silences him and punts him elsewhere in the multiverse. Then the other heroes rally; pregnant Sue Storm, Daredevil, Ghost Rider, US Agent and...seriously, they are fairly unmemorable from that point forward. It's the C-Team plus S.H.I.E.L.D versus deus ex Doom and in the end...well, Doctor Doom only knows how to rule worlds and defeat that Accursed Richards, and he left all of his Richardses on WarWorld.
Despite that, he doesn't kill anyone (if anything, perma-drunking Tony Stark was like...early Christmas. I mean, it's not like the booze was breaking the bank or anything, but it's the thought that counts.). He introduces free energy cells to the world. He rules benevolently (with the exception of those foolish enough to oppose him, who he crushes). Then the Skrulls come, and Deus Doom (yeah, I'm keeping that), just sighs impatiently, wrecks their fleet, and proceeds to trash every spacefaring civilization who so much as points a telescope at Earth with his metal-clad hands. He takes a holiday to free his mom from her imprisonment (which is to an actual devil, not Mephisto, which is weird and surprising) and collect himself some new bling for his metal-clad hands (well, one of them, but it's very blingy, so it counts for two...or five...or infinity).
At this point, he has garnered the attention of The Celestials. Doom informs them that their manipulation of existence is unwelcome and they're invited to leave. They rudely decline, and Doom escorts them out.
Superman, on the other hand, is a creature of image. He must be the honest, unflagging symbol of super-heroism. He can’t appear afraid, despondent, malicious, petty, or deceitful in front of the people of Earth. He must be that. However, it’s not an effort for him. Sure, some days it’s harder than others, but for the most part Superman is merely a part of Kal-El. Kal really is upright, brave, and hopeful. He’s been tested enough that if he wasn’t, he wouldn’t have the credibility that he does.
Doom tries to be something more than he is; he tries to live up to his own overblown image. When Kal-El is Superman, he is simply being a purer form of something that he really is on the inside. He puts aside some of his less-iconic traits and then simply is. That’s the difference between these two characters; both have an inner fire to reach out into the world, but while Doctor Doom tries to add to himself and expand, Kal-El simply sloughs off the lesser parts of himself and is the best part that’s inside of himself and the people he protects. It’s a distinction drawn between those who are looking for meaning and fulfillment from the things around them, and those who are looking for richness in themselves.
Getting back to pettiness, perhaps that ability to understand others enough to accept their small faults and the strength of character to accept it when others point out our own is something that distinguishes villains from heroes. A villain is largely about ego, often carries a personal grudge against their archnemesis, and that grudge is often because the hero reminds the villain of one or more of his flaws. This glosses over ideological and material villains, who respectively have a viewpoint that demands action that brings them into conflict with the heroes (Magneto) or simply want something and don’t care to follow the rules about it (usually banks and what’s inside of them). While each stands in opposition to heroic qualities (except perhaps the ideological, mentioned in-universe during Secret War, when The Beyonder groups Magneto with the heroes because his selfless goals are aimed at improving the lives of others), the ego-driven villain is especially interesting as it applies to Doctor Doom, Lex Luthor, and even The Joker (while The Joker could be considered ideological, consider his obsession with Batman, the modern concept of The Joker as the result of Batman holding himself above other men, and how his focus unravels without a Bruce Wayne Batman to play off of. He’s a response to Batman with a bizarre point to drive home to him personally. While he would like to kill millions (and perhaps one day will) his fixation remains a personal one with Batman. Petty egotism by villains can highlight the hero’s largesse of character. While Clark has had some bad days, you might note that Reed Richards, Superman, and Batman are some of the least petty people in comics. While they might enjoy a healthy, ironic punishment for a villain, ultimately, stopping the chaos and protecting innocents is just another job well done for them. The villain doesn’t matter to them and they rarely ever feel personally slighted. Superman is demonstrably the weakest one at this. In “All-Star Superman, he lights a guy’s hairpiece on fire and now that I think of it, I’m not sure I’m a big fan of that scene. I don’t mind him using his abilities to ‘accidentally’ turn a trick around on someone, but I’m not sure that actively lighting a human on fire is on a list of things that Superman should be doing.