I'm not sure it was malice so much as a move away from dungeon delving and the wargamer-level detail that Gygax liked to put into products. I have trouble believing that, given the resources involved, it was pure spite. The City of Greyhawk boxed set came about a year later, and that is one of the best city supplements ever made for D&D.
IME, it's more likely that someone thought a collection of parody adventures would work, they needed to attach it to a setting, and Greyhawk ended up with it by default. The Realms already had a full schedule and pop culture humor makes even less sense for Dragonlance (still no overall sense for any setting, IMO).