tim: i see what you are saying but its no the same, for a start the effects change on that intro to make it sound different, plus thats not the main sound anyway (unlike chasing cars riff)
if you wanna see a real bloc party riff, play helicopter
i agree that a song doesnt have to have a difficult to play riff to be good, but i think it does have to be slightly more imaginative that a 4 note alternate picking sort of thing.
some of the best riffs are simple to play and contain few notes (ala smoke on the water) but they are musically intelligent, something which snow patrol could never be.
PP: as far as chords go, most songs have only a few chords, its not the amount which is important, its the progression and the rhythm