I think there is a portion of fandom who, no matter how much they profess to like this series or that, never quite accept new series unless they are action. Kagami was a bit of an exception, being written by the author of Mx0, a manga inexplicably popular online in it's day.Kagami didn't have those rankings so far into it's life span. His point about hate on romance nailed my opinion too. Do users have to repeat that garbage about short, stagnant romance manga every couple of weeks?
Kagami was strange, an unusual case. Until the last three weeks it never really ranked poorly, it was generally near the middle of the TOC until the last few chapters. It was canceled months before St&rs, a series that consistently polled much worse. Kagami even sold decently well for a new series. I'm not convinced it was canceled, I really think it is true that Kano chose to stop writing.

