Yet the films endure, and clearly grow richer with age, vehicles of breathtaking power and glamour that cruise effortlessly through our imaginations like a fleet of gold Cadillacs. The qualities that the cineastes see as weaknesses I see as Spielberg's strengths, and as the reason why he is one of today's most important film-makers, the producer-director who single-handedly saved the Hollywood film when it threatened to founder in the Seventies.
Besides, sentimentality and spectacle have a valuable place in the arts, as in the operas of Puccini - though there are puritans who feel slightly queasy at the thought of Tosca and Madama Butterfly. In many ways Spielberg is the Puccini of cinema, one of the highest compliments I can pay. He may be a little too sweet for some tastes, but what melodies, what orchestrations, what cathedrals of emotion...
Spielberg's problem with the critics, I suspect, is that he has always been too American, dedicated to the values of a provincial America - in fact its heartland and ideological engine - they preferred to ignore. A few years ago, at the Hollywood premiere of Empire of the Sun, I was amazed by the hostility that American journalists showed towards Spielberg. One even asked me why I had allowed him to film my novel - one of the strangest questions ever put to me, and with a scarcely concealed sub- text.
These American journalists came from New York, Boston and Chicago, while Spielberg's roots seemed to be set deep in a Norman Rockwell suburbia of soda fountains, beauty parlours and daytime TV, a Fifties vision of the good life still aspired to by most of the planet's population, but one which makes Spielberg's metropolitan critics profoundly uneasy. Perhaps they realise that too much of American culture is based on the sentimentality, naivety and showy self-confidence that they recognise in the mirror of Spielberg's films.
Curiously, Spielberg's childhood was not especially happy. His parents were divorced in his teens, and a series of wrenching family moves led him from small-town New Jersey to an Arizona suburb, and eventually to anti-Semitic northern California. He was gawky and unpopular, but his father's 8mm Kodak camera saved him.
At the age of 14 he made Escape to Nowhere, a 40-minute war film for which he recruited his mother, sisters and friends, and followed this, while still at school, with Firelight, a full-length science fiction feature that his father screened to a paying audience in a specially rented cinema. Later, while nominally a student at a Long Beach college, he spent his spare time haunting Universal Studios, and his sheer persistence led to a contract as a director of TV movies.
With Duel, one of the best-ever made-for-TV films, he displayed most of the qualities present in his subsequent blockbusters: the absence of stars or glamorous roles, the suburban characters and locations, the down- playing of dialogue and dramatic complexity in favour of a relentless, through-the-windscreen view of the road ahead.
It is, however, Spielberg's apparent shortcomings that most concern John Baxter in his absorbing book, Steven Spielberg: The Unauthorised Biography (HarperCollins, pounds 18). They seem to give him a nagging headache that one can sense on almost every page. Baxter is a shrewd, witty and very readable writer who has produced superb biographies of Fellini and Ken Russell, directors with something of Spielberg's bravura talents.
But Baxter is clearly uncomfortable with Spielberg, who unsettles him by thwarting his best and worst expectations. Baxter points out that, by the late 1970s, Jaws and Close Encounters of the Third Kind had brought Spielberg a fortune of some $200 million. But while traditional Hollywood moguls rolled around in stretch limos and dined at Ma Maison and Spago, Spielberg lived frugally, drove a rented car and dressed in jeans and trainers.
In Baxter's eyes, this behaviour merely reveals Spielberg's perpetual adolescence. I would compliment him on his indifference to convention as he pursued his unique vision. Baxter repeatedly emphasises that the imaginations of Spielberg and the Movie Brats - Lucas, Scorsese, Coppola et al - were entirely fed by the films they had seen in childhood, an accusation he wouldn't dream of levelling at, for example, a novelist who had passed his formative years in the library.
Film, for most of this century, has been a far more serious medium than the novel, and the Movie Brats and their encyclopaedic knowledge of film from the Lumiere brothers onwards compare favourably with today's film students, for whom the original Die Hard and Terminator represent all the history they feel they need to know.
Baxter quotes an unnamed colleague who says of Spielberg: "He has all the virtues - and the defects - of a 16-year-old", and refers to him as the Peter Pan of movies, the Boy Who Wouldn't Grow Up, who preserved himself in an artificial adolescence. But boys who won't grow up soon find themselves in remedial institutions, and do not control the giant entertainment and media conglomerates that increasingly set the pace of the world's economies.
The Spielberg I first met on the Empire of the Sun film set in 1987 struck me as highly intelligent, hard-minded and wholly adult, a visionary who accepted that the age of sophistication is over and that the benevolent technologies that govern our lives are happy to welcome the era of the naive. Throughout his films Spielberg is using the global entertainment culture to explore those constants of our everyday lives that we all take for granted - the wonder of existence, the magic of space-time, and the miracle of consciousness and childhood.
Were it not for Spielberg's high-concept cinema and the huge audiences and revenues he attracted, the Hollywood of the 1980s would have been stranded among the disappointments of late Kubrick, Coppola and Cimino, sustained by little more than the empty Star Wars spectacles of George Lucas. The resistance to Spielberg expressed by Hollywood's old guard only confirms their grudging debt to him. Given that Hollywood is a company town, and that in company towns everyone respects the man who signs the cheques, it is significant that Spielberg had to wait until Schindler's List - the least Spielbergian of his films - before receiving his first Oscar.