this is common for all anime type shows brah theirs going to be a delay regardless of how popular/successful a show is. in the case of Japanese anime , the creators eat of dvd/blu ray sales and toys and other things that can speed up the process but in the case of the boondocks it doesn't have that Asian Fan-base support all like that.
the american fanbase is strong but where not buying dvd/blu rays like our asian counter parts
Take Fairy Tail for instance , very popular in japan, had an American fanbase , great blu-ray/dvd sales
and the show was still cancelled due to the price of production.
http://dailyanimeart.com/2013/03/02/fairy-tail-anime-cancelled-on-30th-march-2013/