As for the talk of the Nielsen ratings system being "dead," it's still the primary way networks evaluate whether to renew or cancel programming.
Surely so, in the near term. But that cannot last if they plan on surviving. That original series are now being produced entirely outside the Nielsen ratings system and succeeding (cf. House of Cards) is just a further indicator of the way things were already going.
(One among many: how many people do you know, for instance, who still watch network TV in a "live eyes" fashion at the pre-appointed time? I haven't done so in years -- barring the occasional insomnia-driven viewing of a Two and Half Men
rerun -- and can't think of many people I know who do so either. I know more than one household where they don't even bother with network television anymore, they just watch shows on Netflix.)
Saying that the ratings didn't matter for Battlestar Galactica just isn't true.
It's also not what I said. I said it was proof that the traditional ratings system was dead: it was no longer accurately measuring the market for the show. It obviously "mattered" to whether the show was cancelled, and obviously the Nielsen ratings system will persist for some years yet -- a dead thing can take a while to stop moving. Nevertheless unless some radical change occurs in the trends, it's quite clear that the model the ratings system was based on is increasingly obsolete.