While not created on the spot - players have already made missions in the game for the 15th anniversary events. https://www.everquest.com/news/15th-anniversary-player-missions
I do remember that The Elder Scrolls (3) Morrowind (or Daggerfall ?) had a zone construction kit. There was also the "Bard's Tale Construction Set", Forgotten Realms: Unlimited Adventures and similar software during the 90s. Players made many great maps/zones for Unreal Tournament, where they even added reconstructed zones from other games. One of the most popular was a giant nursery, where the players appeared to be very tiny. They were able to run on shelves and hide behind books and such. Something similar would be great for EQ. A bonus expansion with player made maps/zones could be released every June.
I am sorry, but I don't see sending false hope to players to spam the community managers inbox as humor. Aprils fools day has become a horrible day as everyone tries to outdo everyone else with who can do the best prank.