Critiques of Spielberg, in general, follow much the same lines, and they stem from an academic distrust that dates back to his earliest successes. Here's how it happened:
It all begins in France, in the years after World War II. French cinephiles who had been prevented from seeing American films by the Nazi occupation are suddenly awash in a half-decade of American cinema. The writers of the French New Wave discuss these films in a new, unusually intellectualized way, creating for the first time an academic discipline around the study of the motion picture.
Film Studies arrives in the United States in the '60s, when folks like Spielberg and Scorsese are just getting warmed up. Although film studies began with analysis of the Hollywood system, the primary interest of the academic field is in the films and movements that break Hollywood's rules. In Europe, French and Italian nationalist cinemas rise out of this academic movement in an effort to create distinct "styles" for their own nation's films. They break Hollywood's rules, and are rewarded by the attention of the academic world. They give film theorists more to write about.
In the '70s, a wave of independent film sweeps the US. Indie filmmakers take their cameras to the streets of New York City, churning out gritty, unusual content that challenges Hollywood's basic aesthetic rules. Their films are a gold mine for academic study.
And then there's Steven Spielberg, the guy who didn't really go to film school, who never really bought in to the academic's view, who makes films that don't obviously break any of Hollywood's aesthetic rules... whose work is boring to the academic who's looking for something juicy and obvious to analyze and dissect. And in 1975, Spielberg's "Jaws" becomes the world's top grossing film. The success of "Jaws", followed by the numerous other blockbusters in Spielberg's career, is a slap in the face to academic film studies. It proved the preferences of the academic film world irrelevant. Academia got bitter, and for the next three and a half decades, would either ignore Spielberg's films, or would dismiss them as "infantile" (as a professor of mine did, almost ten years ago).
What a lot of the academic world missed, and what some today are discovering, is that Spielberg's adherence to one particular rule blinded them to almost all of his cinematic innovation.
Classical Hollywood films were always made with a primary rule in mind: the apparatus of production must never be visible to the audience! If the lighting doesn't appear "natural", or if the camera movement draws attention to itself, it's pulling the viewer out of that dream-like state of being lost in the world of the film. It's making the viewer aware of the process, the machinery, and the mechanics. It interrupts the escape.
Many independent filmmakers broke this cardinal rule. To them, part of the fun of movies was to be able to recognize the machinery, to spot the silhouette of the man behind the curtain, so they made films that invited that kind of viewing. Academics, in turn, ate it up. After all, it's always easier to dissect those films that invite their own dissection!
Spielberg's films, on the other hand, do not "demand" analysis. On the contrary, they consistently draw viewers to fall in to their narrative spell. I remember my own early attempts to perform some academic deconstruction of a Spielberg film: I tried to identify visual motifs in the desert chase sequence in "Raiders of the Lost Ark" (1981). I had to watch the scene over and over and over again, because no matter how much I tried to pay attention to shot structure and composition, by the end of the scene, I was simply immersed in the film, watching a movie.
"War Horse" is a great film to consider in light of academia's attitudes. On the surface, it's a naiive, wide-eyed story, told in a straightforward, "traditional" way, with pretty images, plenty of Hollywood polish, and not much "art". Since it does not challenge its viewers to analyze it, academia will likely follow the usual trend and dismiss it as unworthy of a closer look.
But look closely, and it becomes an entirely different film. It is (as some critics have pointed out) a film that mourns humanity's use of violence, while at the same time celebrating humanity's potential for civility. Though it's called a "classical" film, it's a war film unlike any other -- there are no "sides" to take, no "good guys" or "bad guys" in the traditional sense at all. It is about as far from a "conventional" Hollywood narrative as you can get, but all the while, it maintains Hollywood's cardinal rule, immersing its audience in the world of the narrative, never allowing us to remember for a moment that we're in a movie theater, watching a movie.
Academia makes the claim (and it's a more complex and challenging claim than might seem at first) that cinema, at its best, is art. Though Spielberg blends his artistry with entertainment, I don't think of his work as any less artful, or of him as any less of an artist (in the cinematic sense) than Hitchcock, Ford or Keaton. In fact, I see cinema's primary goal as entertainment, much like painting's primary goal is decoration, rather than art.