I'm not him but calling the World Cup just another "Quidditch" match is fucking dumb, it's totally different to all the ones played at Hogwarts, in a way I think it was an attempt by JK to justify the stupid scoring system by making matches more interesting and diverse.
And it's not just about the match, it's about everything that comes with it, like the different nationalities at the match, the leprechauns and other teams' mascot fighting each other, the whole vibe. There's also the part with the muggle who has to co-ordinate the campsite who keeps getting his memory erased, and how the death eaters decide to assault him later in an act of hooliganism. All of that is great stuff.
Also lot of it is also setting up Krum as a character, because as I said earlier the book is a whodunnit and he's a suspect, but his act with catching the snitch suggests that he's too honourable to be going after Harry, although of course as a lot of that is taken out of the movie is doesn't matter anyway I suppose