While i think their answer was dishonest, they still would need to take a massive chunk of time to cut out a section of the game that would be self-contained, have it make sense and be happy that it would represent the entire game from a marketing standpoint.
FC2 is about as close as a single player game comes to the complexity of a MMOG. They would need to devote a large amount time to making a demo which would take critical manpower away from the retail product.
Personally, I don't like the fact that there won't be a demo but from a business standpoint it makes a lot of sense.
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"Both the “left” and the “right” pretend they have the answer, but they are mere flippers on the same thalidomide baby, and the truth is that neither side has a clue."
- Jim Goad