These stats are fairly useless in decision making because
(a) going off what streetdragon said, even frequency response graphs often are not accurate at telling us much about the perceived bass impact in comparison to other frequencies; I only find them useful for comparing phones in the same line with similar drivers and enclosures.
(b) these stats don't tell you anything about the quality of the lower bass response (could be a lot of compression at high volumes or distortion at any volume).
(c) without knowing the amount of roll off at the bass end, the stats are completed meaningless. A pair of phones with 20Hz to 20kHz response may have less usable bass response below 40hz than ones with a 25Hz to 30kHz response because the 20 to 20 phones could be peaky in the mid-bass and have more emphasis on the mids and highs, such that the low bass response could be -15 db down from average, where as the 25hz to 30kHz may have more bass emphasis overall and a flatter response down to 25Hz.