I think moments in Seinfeld would play very well animated, and, in that way, yes, the show was cartoony, a word I tend to avoid with Cartoon Network's movement into live-action fare. Nevertheless, I cannot watch George Castanza crossing the street with the Frogger arcade game without thinking of a cartoon version of the scene.
On a related note, David Mandel, a writer for both Seinfeld and the later Curb Your Enthusiasm, worked with Kevin Smith and others on making the Clerks cartoon, which I think is a good indication that the writing style of these shows lends itself well to animation.
