A post starting with "Seth Godin explained.." is a big turn off for me after reading his latest book (it was painful).
I agree with you completely on the large sites benefits, but there is a HUGE difference in the long tail vs main keywords.
Top queries is what converts well if you sell stuff. People who want to buy something use short queries. People who are looking for information use long queries. Thus long queries fit better for our adsense model.