If you were designing a product used on small speaker systems (without full bass response) would you modify the design to make up for the system's lack of bass at the expense of being "flat"?
Let me ask the question in reverse.
Would you design a product knowing that when it's played there would be a lack of bass just to be able to say its response is flat?
It's an interesting question. It's the same question I suspect face designers of automobile gas gauges. Knowing that most people will push the limits of the tank empty warning do they lie and give a "fudge factor" so you don't run out and curse the car? I am guessing most do.
I've been thinking about this question and a "flat" frequency response has meaning to users only in the sense of the final outcome.
Small speaker + bass boost = flat sound.
Small speaker + flat response = rolled off bass.
The choice seems obvious.