In a Gamasutra interview with Michael Pacter it is explained how EA will soon offer extended demos that you will have to pay for. Extended seems to indicate 3-4 hours of gameplay but that's half of the standard game length these days and in some cases the whole thing (Rogue Warrior / Terminator Salvation anyone?). The touted amount seems to be $10-$15 which is better or at least on par for price and length of the various game DLC being released. Still, what should be used to market this is pre-orders; I buy said demo for $15 and get the full release for $15 off, plus be able to use my existing saved games. Not implementing something like this just makes it appear to be the money grab that some associate with DLC and collector's editions.
Proving what pirates are saying to be true when they paint you out to be greedy fat-cats is not in your best interest.