Best of All Possible Worlds

"Once one dismisses the rest of all possible worlds, one finds that this is the best of all possible worlds."

- Dr. Pangloss, Candide

""The optimist proclaims that we live in the best of all possible worlds; and the pessimist fears this is true.""

- James Branch Cabell, The Silver Stallion (1926)

Ever wonder what would happen if something in your favorite series changed? Do you wish The Scrappy had never been born, the Big Bad would get his comeuppance, or that The Adjectival Superhero and his love interest would just get married already?

Well...

Look! It's an Alternate Universe, in which all of these "problems" are fixed! Let us see what happens:

Oh noes! This other universe is a terrible place! Tropeman's enemies have discovered his secret identity by hacking the internet, and now they've horribly murdered his wife. Since the Big Bad is in jail, the power-vacuum caused by his absence has resulted in an even worse villain stepping up to the plate, and now Cthulhu is running for president. Also, The Scrappy was somehow responsible for preventing World War III.

There now. See how terrible change can be? But don't worry, we can fix it: at the last moment, a magical imp shows up and changes this universe into an almost perfect copy of the original one. Now Tropeman and his girlfriend are in an unsatisfying quasi-dating relationship, the Big Bad is causing trouble, and The Scrappy is getting plenty of screen time. Everyone's happy!

In other words, the canon is treated like the Best of All Possible Worlds for the characters, and an Alternate Universe / Elseworld / What If has two options: have a Downer Ending, or revert to match the original canon. Hitler's Time Travel Exemption Act often runs on this.

See also: Rubber Band History (the general tendency for alternate histories to end up more like the "real" history); It's a Wonderful Plot (a specific history change that almost always makes things worse).

Anime And Manga

 * Inverted (so far) in Rebuild of Evangelion. It is by no means a happy place, but (so far) no main characters have died, making it markedly happier than the original Neon Genesis Evangelion.
 * Deconstructed and back in the series Noein. Haruka has the ability to jump dimensions, and spends an episode or two observing possible parallel or future time lines. One is 'perfect' in a Stepford Smiler kind of way, one is seriously post-apocalyptic, and most are pretty average, but after all of it she comes to decide there really isn't a best world, and even if there was, it's really not where she belongs.

Comics

 * Pick a DC Elseworld. Any DC Elseworld.
 * And throw in the old "Imaginary Tales" for good measure. Superman and Lois Lane get married and have kids? Something goes horribly wrong. And the moral of the story, dear children, is that Superman should stay single forever for the safety of himself and others.
 * Averted in the Imaginary Story "Superman Red and Superman Blue" after accidentally splitting himself in two, Superman not only fixes all of his personal problems (now he can marry BOTH Lois Lane and Lana Lang!) he also turns the world into an Utopia (thanks to the Super Intelligence he also conveniently gained) curing all diseases and turning ALL criminals good.
 * This was the heart of the original Marvel Comics What If? series. Only one or two stories ever came out happier than Earth-616's story. (Ironically one of the few that had a happy ending was a version of the original Clone Saga years before The Clone Saga came to be rued in the minds and hearts of fans.)
 * Avert in the Ultimate Wolverine vs. Hulk. There's a seen where Cap and Tony are seen playing table tennis, one of the characters states they had an aweful dream in which Civil War took place. Both of them laugh and assure everyone that it would never happen.

Live Action Television

 * The Buffy the Vampire Slayer Alternate Universe where Willow and Xander were vampires and its Rocks Fall, Everyone Dies at the end would qualify.
 * Though given the point of the episode wasn't so much that the world they had was good as that Buffy had done a lot less harm than good over the course of the series, the bar is set low enough to be highly reasonable.
 * Anyanka invokes this, or possibly its inverse, in the climax, by saying he doesn't even know what the original universe was like; Giles responds "it has to be better than this." Smash.
 * In Doctor Who we have the alternate universe created when Donna turns right in "Turn Left", which causes the Doctor to die at the Thames Barrier when he defeats the Racnoss, and several contemporary attacks on Earth to cause mass casualties, and/or wipes out several of the Doctor's allies (including Martha, who he never met here). Naturally, Donna set her timeline back on its proper course at the end of the episode.
 * A bit like the Buffy example above, this setting is about the hero not being around to save the day for the past couple seasons, and therefore hells yeah it was better when he was!
 * Amusingly, Fridge Logic hits very early, in that, to keep Donna alive long enough for Rose to beam her over, the lethality of a whole bunch of neutered threats had to be toned way down to non-world-destroying levels. Britain was choked with refugees and Putting on the Reich and it was all getting quite dreadful, but the human race hadn't been extinguished as he's so fond of predicting it will do if he fails.
 * Well, a lot of those other people died averting, just less well, so there were repercussions. Sarah Jane was on the moon, for example, and Torchwood Three died in something or other the Doctor had originally handled. Leaving Wales vulnerable to all the stuff they originally saved it from...
 * Played with in Fringe after . While many things have changed, the bad things and the good things changed are sprinkled evenly across both universes, and no Reset Button seems forthcoming.

Western Animation

 * The Family Guy episode "Stewie Kills Lois" deals with Exactly What It Says on the Tin. Stewie finally carries out his long running threat to kill his mother.
 * Most of Futurama's "Anthology of Interest" episodes are like this.

Real Life

 * This is one of the arguments against the Problem of Suffering, especially suffering created by nature. Designing creation any other way would have to other, more destructive consequences.