The fact is that 30 or 40 years ago very few speakers measured flat across the frequency band. Does that mean those speakers sounded bad because they were not "accurate" as perceived by many audiophiles as "the last spoken word of hi end reproduction." Again I respectfully disagree with the notion that a speakers "measured frequency range" is the most important factor in sound reproduction.
Most of these measurements are meaningless to begin with because most people that do these measurements use different techniques not to mention that these measurements are often taken in anechoic chambers. We do not listen to music in anechoic chambers, or at least most of us don't. Secondly, even when a tech does take these measurements in a normal room setting, we are led to believe that every room will be constructed identically to that room that the measurements were taken in. That is we again have to believe that everyone will use that speaker in a room that has the same treatments, same room construction and boundaries.
Many of the speaker designers in the past did tune their speakers by ear, and many have gone back to doing that in the here and now. And I would argue to kingdom come that many of the finest speakers I have ever listened to were anything but flat across the entire FR. There is invariably differences in mid-range suck out and other diffraction's that play a major role in how we perceive a speaker in the room in which we listen to it. I would much rather listen to a speaker that has smooth continuos roll off at and beyond 15khz, than a speaker that stays flat all the way out to 20khz. To me a gentle roll off is the way I prefer a speaker, especially with more on an emphasis on natural decay and timbre cohesiveness as that decay swims over my head. To me the midrange is where a speakers tonality is born and where it lives.
Again not everyone will appreciate the same qualities, which was my point as to why some speaker manufactures strive for something less than a totally flat frequency response throughout the entire band.
This article is a good read for those that may appreciate such qualities.http://www.stereophile.com/asweseeit/138
Again I am not advocating that engineers should not strive for a flat frequency response, but there are subtle changes in a frequency response that can make a speaker's attributes shine through, while still maintaing a level of accuracy in a more cohesive manner.