Because even though it declined badly last season, I thought maybe that was a fluke and that it would recover. Far from it. This season just brought more inane drivel and ludicrous moral angst.
There was no reason to "dump on it" before. Now, there's getting to be less and less reason to watch it.
As to why I continue to watch? I guess hope springs eternal. But if the next season reeks as bad as this one, I won't have too much difficulty deciding.