I look on this differently - The rule was that engines must meet certain tests in very controlled test conditions. Most manufacturers spent millions getting their engines to meet the standards ONLY at the test conditions - outside these conditions they produce "wads" higher levels of pollutants. VAG merely did the same thing by a software patch.
Most of the protestations are what I term"holier than thou" as the other manufacturers produce just as much pollutants in real world conditions. What REALLY needs to be done is to have tests that are a reflection of the real world. Then, and only then, can proper comparisons be made.