Stephen Sondheim is depressed by the West End. "When I scan what's on," he told The Times on Saturday, "my heart sinks into my boots." As on Broadway, he sees on Shaftesbury Avenue nothing but "commercial crap" which must be slightly upsetting for the authors of Billy Elliot, Matilda, Chicago and Les Miserables, not to mention Alan Ayckbourn, Alan Bennett, Zach Braff and the estate of Noel Coward.

It's all very well to dismiss Wicked as "an event" rather than a show, but there is a danger here that Sondheim's own high standards of operation have seeped into a cul de sac of critical opinion when it comes to looking at what's around him. I probably dislike Legally Blonde as much as he does, but I'm realistic enough to understand its commercial appeal and also the necessity of that appeal.

For if the West End was full of Sondheim shows, the place would be dead. But presumably, in his eyes, the West End list is salvaged by the arrival next Saturday of his acclaimed Sweeney Todd from last year's Chichester Festival Theatre.

Sondheim is also on record as saying that Floyd Collins by Tina Landau and Adam Guettel (the grandson of Richard Rodgers), newly revived at the Southwark Playhouse, is the best musical of the past 25 years. It's certainly very good, but there's also a very good reason why it's never been presented on Broadway and is unlikely to transfer from the Southwark vaults to the West End.

Instead of transporting an audience to a higher plane of delirium, an ecstasy of musical theatre heaven, Floyd Collins keeps you pinned back in your seat thinking hard and seriously about what you are watching and listening to. Finally, like most of Sondheim's own musical theatre pieces, it shuts out the audience, denies them access. It's trying too hard to be art.

Now, this may be a very good thing. And there are days when I consider, say, London Road, or Sondheim's own Passion (which I really can't stand), and I think that this is the way forward. It may well be the way forward for Sondheim, for some critics and for musical theatre aficionados. But it's the exit sign for the popular audience.

Lyn Gardner of the Guardian said to me at the Southwark Playhouse on Friday night that Floyd Collins is a musical for people who don't like musicals. I'm always puzzled by this kind of statement (people who say they don't like musicals never think twice about going to the opera) and challenged her on the definition of "musicals" that people do like.

"Oh," she said airily, "Singin' in the Rain and Andrew Lloyd Webber, those kind of musicals." I know what she means, but the lofty dismissal of anything that might be too obviously pleasure-spreading in a large popular audience always carries with it the short-circuiting of serious critical appraisal, certainly in the case of Lloyd Webber.

It's interesting that the Critics' Circle will on Friday give a lifetime achievement award to Sondheim, who represents, in their eyes, critical respectability, whereas Andrew Lloyd Webber, who's had infinitely more success with the British public, and has never been taken seriously by the critics (despite the fact that he shares a birth date with Sondheim), never even makes the short list in those discussions.

Ah, but success cannot be equated with artistic respectability, the cry goes up. And we hit the wall. The more difficult and more recherche, the cleverer, something is, the more respectable and award-prone it becomes in the eyes of the critics.

Actually, I'm not alone in thinking that Lloyd Webber's score for Love Never Dies is one of the finest of his illustrious career. I was listening to a recording of Mascagni's Cavalleria Rusticana the other day, and it's as good as that. But it's clever, too, in embracing other, modern musical idioms in a way that Sondheim, perhaps to his credit, always eschews.

The Book of Mormon? "A fun college show," sniffs Sondheim and he may well be right. But he may well be wrong, as he is wrong (and curiously bitter) about so many other things and people in his provocative annotated collection of lyrics, a publication, incidentally, that has made him odds-on favourite to win this week's memorial Sheridan Morley prize for theatrical biography.

The only point of awards, says the sagacious composer, is the money. Has anyone yet told him that the SM prize only comes with £2,000? Well, at least that should buy him a few West End theatre tickets to actually see the shows he's so pompously dismissive about.

Oh, and he's wrong about awards, too. The point of awards is to give wider public attention to deserving artistic projects or artists, and they're always most effective when the project or the artist really needs the recognition (or indeed the money). Giving Sondheim another award is like giving an obese man another chocolate cup cake. He's had enough already, and one or two more won't make any difference to anyone.