Most great speakers are "voiced". Even the famous Quad electrostatics were voiced - I remember Peter Walker explaining in an interview how he did it, and the different options he took for the ESL57 and ESL63. If you look at the example of the "good measuring speaker" presented in the triggering Soundstage letter (the Magico M5) it is clearly voiced.
Can you tell us which speakers you have owned or listened you consider that are not "voiced"?
BTW, if people would spend some time looking at ALL the published measurements, including the room averaged, they would find that most flat speakers have horrible in room measurements and the "abysmal engineering failure" symptom disappears in most rooms. I would say that most people voice their speakers for anechoic chambers, happily some great designers voice their speakers for the audiophile listening rooms.