Steve, good post. The answer to your question is simple: Most speaker designers don't know the physics behind designing a time/phase accurate speaker. It's much easier to claim that it's not audable. I suggest that anyone owning a pair of well designed time/phase coherent speakers for 6 months would never be able to go back to what most manufacturers claim as "hi end" again. I have been listening to Green Mountain Audio speakers for the last 3 years and I can now hear the crossover in every non time/phase coherent speaker I hear.
Live sound direct from an instrument to our ears does not have delay that changes with frequency superimposed on its original response. It is an artifact of speaker physics. We would not tolerate such phase smear in our consoles, mixing boards, amplifiers, pre-amps or any other piece of gear. As speaker technology improves, the remaining clues that we are listening to speakers, such as distortion, horn signature and other artifacts, are reduced. Phase delay is a subtle but critical clue to our ears, and its reduction puts us closer to the real thing. All other things being equal, the speaker with the flattest phase response sounds the closest to being there live. Every time. To claim that our rooms cause problems therefore we should accept phase shifts on the order of one full cycle from our loudspeakers does nothing but fuel the fire for the designers that lack the knowledge to build a time/phase coherent product.
Live sound direct from an instrument to our ears does not have delay that changes with frequency superimposed on its original response. It is an artifact of speaker physics. We would not tolerate such phase smear in our consoles, mixing boards, amplifiers, pre-amps or any other piece of gear. As speaker technology improves, the remaining clues that we are listening to speakers, such as distortion, horn signature and other artifacts, are reduced. Phase delay is a subtle but critical clue to our ears, and its reduction puts us closer to the real thing. All other things being equal, the speaker with the flattest phase response sounds the closest to being there live. Every time. To claim that our rooms cause problems therefore we should accept phase shifts on the order of one full cycle from our loudspeakers does nothing but fuel the fire for the designers that lack the knowledge to build a time/phase coherent product.

