Let me explain why.
Toonami, right now, does not appeal to adults. It does not even appeal to teens. I could see maybe pre-teens liking it if the quality of the programs were better or if Naruto and One Piece aired at the front of the block and everything Dragon Ball and Hunter x Hunter could be thrown out the window, but really you have one high-quality show, which will not garner good ratings because of the time it airs at and the ignorance of anime fans (Gundam Unicorn) and a really weird show which is still all right to watch (JoJo), but everything else is pretty lame.
The content ratings for all the shonen on Toonami are total lies. Dragon Ball Super could be on CN at 9am for toddlers honestly. Yeah, so Toonami's gonna get cancelled because everybody wants to see quality stuff, and, in addition to being for babies, the shonen are pretty lame.