As a newbie, my observations on C&C are as follows.
Polarised C&C, like what night86mare has pointed out seems to be the norm in CS. Patting friends on the back is also inevitable, as the forum grows and cliques develop. It is impossible to eradicate these 2 issues. If anything, these 2 traits are core as to why CS population is growing. Patting each other on the back is mutual morale booster, whether or not the photo is good is irrelevant. Also, commenting on photos and supporting fellow clique members further enhances bonding, again, photo excellence is irrelevant.
Coming back to C&C on photos, I could be wrong, but I have this nagging feeling that C&C provided towards newbies are different from C&C provided towards friends / buddies / senior members. To illustrate my point, newbie and senior submit same photo for C&C. Newbie can get thrashed for various things which are mostly technical like picture not sharp, dark areas not exposed properly or the rules of composition not followed etc. On the other hand, the senior member's photo will probably receive comments like good bokeh, artistic use of light, unique perspective etc etc. So after a while, which newbie wants to post for C&C ?
Someone earlier on observed that even senior members either slow down or stop posting pictures. Most CS members, especially hobbyists hang out at CS to gain a sense of belonging. If in the process they learn something, great. If not, no loss since he is photographing for his own enjoyment. He doesn't need to perfect his shots so that he can earn a living via photography and he certainly didn't come here to be chided by people.
If the objective is to develop CS into a forum with great photos posted by its members, then focusing on C&C so that the general CS population buck up is one way forward. However, if only 10 % of the population supports this notion, but the other 90 % remains dormant and are happy just to browse B&S, discuss equipment or join outings to widen their social circles then getting all worked up about C&C and what C&C can do for CS may be barking up the wrong tree.
Its time for me to stop writing .. its like more than 2 caterpillars worth already

Thanks for reading.