1. The stagflation the U.S.A. have experienced recently is taking its toll in box-office receipts (notably 3D films) -For more information see http://mayersononanimation.blogspot.com/2010/12/bad-year-at-box-office.html -
2. WBA has severe production delays in most of its new shows (The Looney Tunes Show will premiere in March -if we have luck-, after being originally scheduled for November)
3. The negative reviews of both Cats and Dogs 2 and Yogi Bear (I am going to watch the latter in the most part for the cartoon) have discouraged the studio stalwarts to produce new shorts (I don't think if this would be a reasonable belief, as Coyote Falls was -really- very near to be nominated for an Oscar)
4. Simply they ran out of ideas...

Well, you can give your point-of-view about this. See you later.
P.S. While I did the same thread on the Big Cartoon Forum (http://forum.bcdb.com/forum/There_Will_Be_Theatrical_WB_Cartoons_in_2011_P111088/), the lack of recent replies forced me to look for other sources
P.S. 2: I've just have added a poll, so you can give an opinion with one of these hypotheses.