It's a mature cartoon, kiddy networks wouldn't work for it.
I do agree that Adult Swim would have been a better place for it. BET is a terrible network now. Ever since Bob Johnson sold it to Viacom it's completely gone down the gutter. I also think putting it on a network like BET alienates it from the general public, who - if they aren't either African American (like myself), into hip-hop, R&B or Soul,etc - might not think the show is geared towards them and pass on it.
If it would air on CN at night, it would get a bigger gathering plus CN seems to know how to promote their shows. With a character not as well known, it's kinda counter productive putting it on a Network that appears to only cater to certain people, rather than everyone like CN.