I saw a PR5 domain that had no backlinks at all according to their own search, so I fail to see how PR is any indication of anything really. I know of a PR5 site that gets about 12 uniques a day. We are PR2 and get 100-125. Ranking and it's importance is dependant on what kind of site it is. There are some genres that do quite well without getting a super high ranking in Google. It's a matter of making the right connections, but even more importantly, providing unique content that will get your name recognized by word of mouth which will get you traffic very quickly and without such rankings. I think if one spends their time worrying about the content and less about the rankings, that it all evens out in the end. But again, it would depend on the kind of site and the saturation of that subject. If you are in a highly competitive market share than yeah, the rankings become mucho important. It just depends.