They are cancelling it because it must not be getting good rating, and no one is buying advertising slots around it. Therefor, no one's getting paid.
A show can be critically acclaimed, but if the major people are not watching it, or the demographic sucks, the advertisers will not want anything to do with it. So, CN's pulling it out to make room for something else.
Shows get cancelled all the time. It's a damn shame for some of the good shows out there, but people don't always watch something that's good.
Sidenote: I don't know what the Nielson ratings for these shows are, but most of the ratings you see are not the real official stuff, I think.