I've been thinking about this for a while already... as far as I can figure, excessive chlorophyll in a finished plant does tend to mask the flavor of the resins.

Therefore, artifically inducing a nitrogen deficiency, which in turn causes chlorophyll to break down, allows for other compounds to become noticeable.

On top of improving the flavor, it also seems to allow the OTHER pigments- the reds and oranges and purples that everyone loves looking at- to show.