Agreed. Although there has been a considerable amount of "unsuitable" material make it to the front page of HN, there has also been a lot of pointless citation of this unsuitable material - to the degree that it dominates constructive dialog taking place.
HN is changing, no doubt, but as has been pointed out time and time again on HN, if it is of interest to the community at large, it belongs. The community is changing (undeniable) but, maybe it is that sometimes posts other than an amazing O(N) bubble sort are also of interest...
I, for one, enjoy chuckling at XKCD - typically I just go there myself (without the aid of a social bookmark site!), but perhaps this one is just relevant enough to make it on HN... Or maybe I am wrong.