Definitely useful.
Will make partnering easier. One speaker might have a bright spot at 15Khz. You might have two amps, one with a dull spot at 15Khz, the other at 12Khz. You want the second amp, but both are listed as 'good with bright speakers'. yanno.
Also, when you look at the impedance curve, you can see how difficult they might be to drive. If the impedance of an 8 ohm nominal speaker (measured at 1Khz) drops down to like 2 ohms at 40hz then you know the bass is gonna need a lot of power out of the amplifier. On the other hand, if it goes really high, like 16 ohms then you know that it will be easy to drive but perhaps lacking a little in clarity - relying more on the cabinet resonance to maintain the low end response than the driver motion. In actual fact, they all drop as you go down in frequency, pretty much, until you reach the speakers rolloff point.