Everybody's ears are different... So, if something measures "flat," that's not necessarily how my ear hears it; so, for my pleasure factor, I may prefer speakers that rise in the high frequencies to somewhat offset my ears' drop in highs, as a simple example.
The point about Bose is well-taken. It depends on the audience and the application. While not my primary listening speakers, I have a pair of original 301 v1, refoamed woofer of course, hanging by wires under my porch awning. We play poker out there. Everybody including me loves the sound, in that application. We're not critically listening, and it doesn't matter: we like it.
A speaker series that defies the "measure flat = great" metric is of course the Klipsch Heritage series. The sort of "it ain't perfect but it doesn't even matter because it sounds so very engaging" experience that many people, most critics included, adore. Even the Heresy IV have moved me to tears on occasion, and I "grew up" as a neutral leaning sort of guy. They're like a gateway drug... it's hard to go back to more laid back sound, once you get used to 'em... and the problem is, they have me jones-ing for more: Forte IV, here I come???