So the Ordinary Boys are too ordinary to be magical? Heh, excuse the bad pun. Well I think that by adding pop music, the director was trying to reference the "ipod phenomenon" among the teens in our world, and show that kids in the magical world aren't much different. But perhaps doing what they did for the Weird Sisters in Goblet of Fire
might have been better. Three songs were written specifically for them to perform in the movie, as I remember.
True, Philosopher/Sorceror's Stone
did well to introduce "Hedwig's Theme" (aka the "Harry Potter main theme"), and I must say that theme gives the movies a very magical feel. John Williams must have been proud that his tune continues to influence the soundtracks long after he's stopped work on them. But for me, John Williams just got better and better with his work on Harry Potter
, such that by the time he decided he'd had enough of Harry, which was after Prisoner of Azkaban
, he'd produced a whole set of beautiful themes.