OK Michael - you tempt me to digress.
I think we can all tell that this is a fairly hopeless case, once it is put the way you do put it - and this is how it generally will be put.
The fact is that music education just doesn't fit into regular school teaching - as your characterisation of your school music lessons illustrates. As you and some other readers of this Forum will know, my own children were educated in the independent sector, and additionally had all the nice middle-class individual instrumental music lessons that could be asked for. And when you think about it, such individual education is radically different from normal class learning, because there are no constraints other than their own on how fast a pupil learns. So if they are able and hard-working, kids can make amazing progress; whatever happens, they don't get bored, because if they do, they drop out. So far, so elitist - although it would be nice if such opportunities were open to kids whose parents were not so well off.
And of course this doesn't just apply to classical music - pop, rock etc. require a similar level of skills.
But music is also inherently co-operative, and while individual excellence is important, however good you are, you have to listen to the other people you are playing with. In this, I guess it's like football and other team sports, but overall less competitive. As such, I think it has a valuable place in a general education, and the process whereby music education has become so much the preserve of the already advantaged disturbs me greatly.
The only solution, I think, would be to reduce the scope of the National Curriculum to focus more on those general skills which allow people to take an active role in society - e.g. ability to communicate and calculate accurately - so leaving schools more scope to decide themselves how they educate kids for the remainder of the time available. It's what independent schools, to some extent, are able to do, and why they attract parents, however crazy the fees.