There are 75 years of the BBC to review this week, so let's keep it personal. The corporation has been putting out one of the most populated music videos in history to thank us for our support. Well, we didn't ask to be thanked, but support it has certainly had. For most of us there has been no choice in the matter - not until lately, at least.

The post-war generation feels most warmly about returning the thanks. A rounded musical education, in the terms of the Sixties, could hardly have taken place without it. On the one hand we heard a dramatic increase in the amount of broadcast classical music as Radio 3 succeeded the Third Programme. On the other, the Light Programme always struggled to keep up with the pop explosion, but it was still Saturday Club that had the Beatles and the rest of them performing live before they were totally famous. Later, Leonard Bernstein was on TV showing not just how symphonies worked, but what they felt like. The broadcast range was all of a piece with a world that engaged us with music through competent school choirs, affordable local teachers, and do-it-yourself blues bands; through accessible Penguin Books and well-stocked public libraries and up-to-date record shops.

Take a closer look at the current video, and something has changed. The message is that these assorted musicians share the same airwaves. But the whole of musical life no longer seems to be there. In the meantime, as well as the continuing pop explosion we have seen further waves of growth: in early music and jazz, in new music, most recently in world music. Most of them passed the BBC by in their initial stages, and left it struggling to catch up. With early music it has just about got there. Jazz is still kept in special corners of the networks, and the rest has hardly begun to happen even now - except for the BBC's own brand of new music, a strange brew of publishers' fads and university teachers' fancies that successive Radio 3 regimes have never managed to assimilate into the wider world (see "Sounding the Century" for the current attempt to rewrite musical history as a justification for present-day policy).

The experience of Sixties pop now looks like a portent. Everybody knew then that the pirate stations were the ones in touch, and the repackaging of Radio 1 was a bit of a joke, an elderly relative taking a facelift but unable to replace the hormones. We still see the BBC doing well now what it did well then: a wide-ranging classical repertoire, now with more opera than it used to have, and the chartbusting end of pop. Some of the most heartening trends - typically uncelebrated unless they seem threatened - have taken place through the steadily developing scope of the radio World Service and the arrival of an international television channel.

But the rest? Look instead at the upsurge in live music of all kinds, the diversification of the airwaves, and above all the easy availability of recordings. No single station stands a chance of keeping up, though it could try to show a fair balance.

We are absurdly attached to institutions in Britain. We seem to care more about them than what they are for. The monarchy is the classic case. Closer to home, the Royal Opera House has a higher public profile for rows about its upkeep than for what it performs. If you are in reach of Meridian TV's pre-recorded arts debate this Sunday you will see a programme dominated by intense talk about one set of institutions funding another set, and almost devoid of passion about any kind of art.

We find it easy to look back and celebrate 75 years of the BBC. But is it the BBC we should support, or the music it enables us to hear? What is the best way to deliver the desired end? We are not so good at that one. All institutions are a product of the times that created them. If we are too attached to those times, we don't see the need for change. Now we have opted for a government that has stopped defending a shrunken empire and started promoting a properly contemporary culture, we deserve the same from our national broadcaster.