More specifically, Eddie's original story was that he was horror movie junkie who basically went on a rampage killing people to recreate his favorite movies. It was very visceral and, more notably, realistic.
After 9/11, Universal reversed course on "realistic." Jack, who's story already presented him as an undying zombie, was a familiar and far more over-the-top character was brought back and slight adjustments were made to all of the Eddie key art to make him a clown as well.