Although I side with cziffra's frustrations, I must say glBelgedin is absolutely correct. In general, what people need to realise is that movies typically don't affect society; instead, movies tend to reflect society--this is a particularly important argument with regards to movie-inspired violence, etc., but I also think it may be applied here. People have had an increasingly downward-looking view on Classical music since the 1920's on (well, roughly--you know what I mean) and School of Rock is merely a representation of what we musicians view as ignorance and disrespect, and what others view as normal comedy. Because the regular view is that any "classical" piece of music is only for stuffy, boring snobs with no life. Truth is, those "snobs" are typically not snobs at all but cultured people of above-average intelligence who are in short supply and should be treated with deference. I question a society that looks down upon people who are generally smarter and more observant than average.
But, that's how things are now in our perpetually declining world, and movies--which are generally made to make money--aren't often going to opt to portray emotional classical musicians as respectable people that viewers should model themselves after; such movies won't show, that is, except in small indie movie theatres and to select crowds of the rare cultured people.
So, it isn't the movie's fault at all. It's irritating to think about it, to say the least, but unfortunately we're stuck with it. Unless musicians somehow band together (which would be difficult seeing as we're all so bloody disorganised haha) and start a sociopolitical movement about the good of classical music. lol, it's not going to happen. So, grit your teeth, flick the world off, and return to your keyboards! Tally ho...