My earliest memories of table top role playing in a developed campaign world involved The World of Greyhawk, in particular the Kingdom of Celene. In our game in the mid-1980s, Celene was more open than canon probably allowed. The 1983 boxed edition of The World of Greyhawk describes the kingdom as a Rivendalian society that does not welcome strangers, but will still cooperate with the other nations around them for the greater good.
1992's From the Ashes, the reboot of the Greyhawk setting for 2nd Edition, turns the now Monarchy of Celene (perhaps in the years between the settings the Queen felt the term Kingdom was not gender-equitable enough. Friggin' liberal elves.) has grown increasingly isolationist, allowing the humanoid hordes of the nearby Pomarj wage war against the Kingd...Monarchy's former allies in the Ulek states. A fifth column has come out to secretly aid the Uleks, but are not yet in direct opposition to the Queen.
2000's 3rd Edition reboot D&D Gazetteer returns the title of the land to Kingdom (even though it's still Queen Yolande running it. Friggin' wishy-washy elves) and has them completely shut off from the outside without even a mention of the fifth column.
I don't have any kind of visibility on what WOTC did with it during the Living Greyhawk era. A lot of that information seems to have died with the campaign itself. (If anyone can help me out there, I'd love it) Celene is not one of more developed areas of the World of Greyhawk, and you can see how it had evolved in the twenty years of D&D. You can imagine how much the places of interest have changed.
I'm thinking because it was the Greyhawk that captured my attention 25 years ago, the original boxed set is still the Greyhawk that I love. The whole Greyhawk Wars storyline lacked something in my mind. I didn't like what TSR and WOTC did to my Greyhawk. James over at Grognardia has been talking about this a lot lately, everything from Archie comics to the Traveller universe. I started thinking about how many games get invalidated by updates. White Wolf only gave the inhabitants of Chicago a whopping two years before they rewrote Chicago by Night to reflect the events of Under a Blood Red Moon. Each edition of D&D spawns a dramatic rewrite of the Forgotten Realms (for certain) and then either the deletion or dramatic modification of the other settings. My beloved Greyhawk? Pieces of it were absorbed into canon, meaning the setting as a whole is pretty much dead to WOTC.
It's all understandable. For a business to continue growth, they either need to add players or somehow get the existing players to buy more books. The concept of One Rulebook to Rule Them All is fine if you have a day job and are running the business out of your home, but you can't make a living publishing role playing games unless you have a ton of product turnover and a large fan base. So you need to keep publishing. There was a time when all a player needed was a Player's Handbook and all a DM needed was a Dungeon Master's Guide and Monster Manual. Then came Monster Manual II. The Fiend Folio. Unearthed Arcana. The Dungeoneer's and Wilderness Survival Guides. And this was the relatively tame 1st Edition of D&D. Settings are no different. Authors want to make their mark on the game, so they want to cause an event that will be remembered. Hell, look at how often it happens in comics.
What are fans of a setting, be they DM or Player to do? Well, when you're playing StuffQuest, it's not really a big deal. Just modify the stats according to the newest splatbook. When you are a Role Playing Artiste? It gets trickier.
Ultimately, if you have a vision for a game, and believe in it, you will follow it. You will tweak the rules for a game (or find a better one) to achieve your ends. If the publisher puts something out that contradicts your vision, IGNORE IT! I've been out of the D&D 4e Loop for a few months now, but last time I checked, they never had a very satisfying range of options for Necromancy. If I wanted to run a game with heavy undead and necromancy as the focus of villainy, I'd use 3rd Edition or Warhammer Fantasy. It just works better.
Commerce and Art will always be at odds. It's the way things are. The publishers need to make money and rebooting franchises is a proven way of doing so. If you want your world to ignore the events the publisher's metaplot throws at you? Ignore it. If your players don't like it, that's a topic for another blog.