If there are fewer radical films today, it is because. as Paul points out, it is so expensive to make, market, and distribute movies. I agree with the major points of Walsh's presentation, but when he writes that "Art is about showing life, not having a career," I think he is simplifying the situation. Without a viable career, no filmmaker can produce her art. Unlike Emily Dickinson, we cannot produce films and then tuck them away in a drawer for later generations to discover. My scripts and treatments have been praised by many people, but never viewed as commercially viable to warrant the expenditure of funds necessary to produce, advertise, and distribute. My film criticism only took off once I was able to publish on line and get noticed that way: there were just too few pages for all the good criticism that was being produced.
It is fine for Walsh to say that artists need "to be oriented toward bigger questions, questions of society and history first and foremost." But if no one is willing to put up the money for films with that orientation, what can the artist do? And when an artist does manage to round up the funding and make a radical film that are oriented toward the "bigger questions," Walsh is unhappy when the resulting film does not answer these questions and speechify to its audience the way he demands (see his clueless reviews of some of Gus Van Sant's films which are among the most radical in terms of form and content among contemporary directors. Heck, Van Sant got Universal to pay for a shot-for-shot remake of PSYCHO which is actually no such thing and even better than the original. Walsh is equally lost when dealing with the genius of Pedro Almodovar).
About Chaplin: United Artist released THE GREAT DICTATOR since Chaplin was one of the owners of the studio. He founded it with Mary Pickford, Douglas Fairbanks, and D.W. Griffith so that he and they would have a way to release films without having to be beholden to an established studio. The experiment did onlyh so-so, but they tried.