Ed, you've probably already seen the article by Caryn James in today'd NY TIMES http://www.nytimes.com/2007/11/04/movies/moviesspecial/04jame.html?_r=1&ref=movies&oref=slogin that discerns a trend in the movies slated to open this holiday season: "There is blood on the snow in “Lions for Lambs,” blood on the living room carpet in “American Gangster,” blood just about everywhere in “No Country for Old Men.” The more lighthearted “Sweeney Todd” has its singing, throat-slitting barber. “There Will Be Blood” may be the title of a film opening the day after Christmas, but it could be the slogan for this entire holiday season."
Ms. James may not remember (or may not be old enough to remember) the Christmas movie season of 1971, when the big holiday fare consisted of "Dirty Harry," "The French Connection," "Straw Dogs," and "A Clockwork Orange." Also "Diamonds Are Forever" (if you count Bond-movie violence as violence), "The Last Picture Show" (no violence per se that I can remember, but a real ultra-downer), and "Man in the Wilderness" (mountain man Richard Harris gets mauled by a grizzly, left for dead by his partners, recovers, and sets off for revenge).
I'll leave others to (psycho)analyze the endless sociological implications. For me -- not being a fan of the current Ben Stiller, Owen Wilson, Will Ferrell, Vince Vaughn school of movie "comedy" -- the most depressing sentence in Ms. James article: "And every holiday season needs to fill its bad-Santa/grown-up elf slot; this year that movie is “Fred Claus,” with Vince Vaughn as Santa’s underachieving brother."