Although I understand where you are coming from (op) and have made an effort to motivate the posters with 0 replies with atleast a casual comment, i will say this:
I have come to a conclusion that if you have 0 replies and a lot of view, or a very small amount of replies, you are on the right track and are doing something right. Keep shooting and you will perfect your skills to a point where your pictures are on par with the rest of the brilliant images that some of the members share. If you are recieving a lot of positive feedback... well before you even post you images you already know that you are very highly skilled and enjoy the fact that people love seeing your work, the comments therefor are just there as a token of appreciation for the excellent execution.
now, if you recieve a lot of feedback that is (not necessarily negative) not positive, it doesnt mean that your work sucks, it just means that there are techniques that you have yet to perfect and people are giving you helpful pointers. THere are very few posters that I have seen who actually make hurtful comments that offer no help at all. if you made a post with one of these, take every bit of imformation you can from it and practice practice practice. Nobody starts off perfect, while other can advance faster there is still the threshold to greatness. I have recently went back and looked through my pictures a year ago....and felt like puking in my mouth, they are worthless compared to what I take now (i still suck, just a little less
) but are not worthless in the sense that they are the road that you have followed in developing the skills that you will posses at a later time.
thats just my opinion....