Officially? "New direction and plans for the future of the Star Wars line" and "the Clone Wars has run its course."
Unofficially? 2012 sales of overshipped, poorly distributed and disappointing Clone Wars figures were a major letdown (although Canada, Europe and Asia are all getting the first and final wave of 2013 so what's the deal with that?) and the company is complaining about higher wages for Chinese factory workers and cutting corners to compensate. Either way, the Clone Wars line is dead after almost five years.