Note: This article lists examples which take place within fandoms; not the TV Trope's opinion as to whether a change is for the worse. TV Trope doesn't have opinions. The focus is on over-reaction about minor changes.
When the staff of the Japanese site Poupeegirl announced that they'd be replacing ribbon sales with the creation of a real-money "jewel" currency, the LiveJournal community and Japanese forums exploded with outrage, fearing the jewel-only items would be the only special items available and the ribbon items would all be hideous things. The jewels were finally launched, and aside from a "jewel floor", nothing was really all that changed, since they could be exchanged for ribbons at a much better rate than bought ribbons. That didn't stop users from complaining even after the change simply on account of Poupee charging users for currency they'd essentially been paying for before the switch.
Littlekuriboh used some home-made animations for the season 2 finale in Yu-Gi-Oh! The Abridged Series. Of course, that meant ruining the spirit of the series, even if the episode still used around 6 minutes worth of clips from the original anime, and the animation was actually good. Plus he got some other (good) abridgers to voice a few characters, instead of keeping them all for himself. Sorry, but the series is "Ruined FOREVER", kids. Parodied in Episode 48, which has "internet trolls" screaming about the issues mentioned above.
Various Internet Trolls: Why does he keep putting other voice actors in the show?! This guy's such a bitch, ugh! Why is it different?! No more different! I do not like different! Different bad! Me hate different! WHY'S IT CHANGED, WHY?! I'm going to unsubscribe if this happens again!!!
Lampshaded by "Yahtzee" Croshaw when the introduction of an original theme tune and new intro sequence for Zero Punctuation created predictable backlash; the weekly update to his website was titled "You Changed It Now It Sucks". Every week, the video thread is evenly divided between "best one evar!" and this complaint.
TF Wiki, the official Wiki of the Transformers franchise, makes fun of this to the extreme with "GEEWUN", a derogative term applied to people who believe that if it's not Transformers Generation One, it sucks.
Television Without Pity. Bad Sign #1: Three original editors depart a year after Bravo buys the site. Then the site was redesigned to include a lot more widgets, style flourishes and assorted clutter. More editors left. And the site started covering a lot more reality programming, especially Bravo's Top Chef, Top Design, etc. and scaling back some of the previously in-depth recaps with more glib, bare-bones "weecaps." About the only things left from the site as it once was are the Supernatural fangirl bridgade and the recapper Jacob.
The Irate Gamer's Breakfast Rants complain about how certain parts of cereal images changed. For Lucky Charms, it's the marshmallow shapes, while Cinnamon Toast Crunch has him railing against the box only displaying one of the three original bakers. He even ends the rants with "Face it, breakfast is ruined!"
The tendency of geeks (especially gamers) to do this at the drop of a hat are parodied in the series of Hitler rants taken from the movie Downfall.
On 11 August 2010, web review aggregation site Metacritic redesigned their site. Today, they have 8,000 comments of seething hatred.
When the snark floodgates opened after Fark.com redesigned its website, Drew's four-word response became a site meme: "You'll get over it."
College Humor has changed it's Originals intros often over the years, including just recently. It's lampshaded in a Jake and Amir video, when Amir says he hates the new intro "Because it's different!"
A variant happens in the Hardly Working sketch "Sarah's Birthday", where not a SINGLE person remembers the "Happy Birthday song" or how to say it. They resort to singing an alternative song that Sarah hates, but which everyone else loves.
Happens quite often in YouTube videos in mashup videos when copyright is claimed on the any part of the audio. (If copyright is claimed on the video, it is removed entirely.) YouTube offers replacement, royalty-free soundtracks that often don't fit the theme, and don't contain any of the other sounds that were part of the original video.
Marvel Super Heroes: What The—?! gained more haters after it changed from a series of comedic stop-motion shorts, to a series of stop-motion commercials for various products with jokes thrown in.
Multiplearticles have been written about why @Horse_ebooks changed and started sucking (on September 14th, 2011.) This is possibly the weirdest example of the trope, considering that Horse_ebooks is a spambot on Twitter with a strange knack for Word Salad Humor. It turns out that there was a reason for it: in September 2013 it was revealed that ever since that date in 2011, the account was actually taken over by a human as part of an art project that continued throughout the following two years.
Over time, The Nostalgia Critic got big on Character Development, cameos/crossovers and Rewatch Bonus storylines, became calmer, his reviewing style included more analysis (mostly at the end) and bratty rages were scattered around instead of appearing every few episodes. The "Bat Credit Card" fans note basically people who started to watch him because they enjoyed violent acts of anger have complained about this.
Fans of early Nostalgia Chick kicked up a fuss when she stopped doing linear reviews of "girly stuff" with usually only her in front of the camera, and changed it into a Mid-Review Sketch Show with her friends where they looked at anything she wanted.
Jon Tron invokes this during his review of Banjo-Kazooie: Nuts and Bolts, where he complains about all the changes to the game. More specifically, he states that he hates that he has to complain about the change in formula, except that the changes come with bits of the old formula that don't fit the new and detract from the overall experience.