To be honest I think that the ratings system has been on a slippery slope to being immaterial since the introduction of the home VCR.
But now, with streaming, Tivo and all the other methods, it seems that the powers that be are realising that there is much more than just the paper ratings to a show.
Let's put it this way - are there DVDs on the shelves of American Idol, Dancing with the Stars, etc? Cos if the Nielsens were a true reflection of a show's popularity, then Battlestar Galactica should be no-where near the top twenty DVDs, yet consistantly whenever I've gone into a store on week of release, it's been in the top three.
And as that article states, no-one would make spin-offs from a failure.