The Mezzanine

Why was that Diagon Alley bit in there at all?
Because it's wonderful and magical. Because they know that people want to see it. Because it's Harry's first step into a parallel world that he's never known about. People want to see him 'choose' his wand, to marvel at the wizarding world and all the wonderful things it contains. People want the magic. And the film needs to establish the wizarding world as a place that doesn't just contain Hogwarts. Hogwarts is just the school, the world is so much bigger.

I'm not saying the film is brilliant, I'm saying it's a wonderful scene and the film would have been poorer if it had left it out.

My eldest daughter (who read all the books) dislikes the films on principle because they're so different and left so much stuff out.

My youngest daughter wanted all the movies for Christmas last year (after catching a couple on the telly) and we spent several days marathonning through them. She likes them very much.

I don't really feel strongly one way or another. Often the films' choices are baffling, but they are what they are.

*shrugs*

The best argument for them, is vids like this one, because they do offer excellent visuals: Snake on a Plane - Harry Potter.

(It's my favourite Harry Potter vid of all time.)