Does Time alignment and Phase coherency make for a better loudspeaker?

@jjss49 , flat is always the best place to start. It is a reference point from which adjustments can be made to suit. You can tell me you like your bass boosted 3 dB. 3dB from where? Frequency response and group delays can be easily measured with a $300 microphone and computer program. What can not be measured is the speaker's radiation pattern but this can be determined exactly from the design of the speaker. It is important to remember that the room, the speaker and where the speaker is in the room have to be considered as a unit. Frequency response curves can change dramatically just by moving the speaker a few feet. Identical speakers will have different frequency response curve depending on where they are in the room. Even in what appears to be a symmetrical room they will measure differently. It seems that only people who have no experience measuring loudspeakers in rooms think good sound is hard to measure. Once you know what type of      soundstage you like and choose the appropriate type of speaker, assuming the speaker is well designed you optimize the system in your room by measurement. You can not get to the most accurate sound without it. You start with accuracy then tune it to sound good to you.  If you have a shrill recording and have to ability to punch in a Grundy Curve (BBC curve), wonderful. I have one on a preset if I need it.

It's harder than not so easy to have time coherence at the listener ears in a home environment unless your room is an anechoic chamber. It impossible because of reflections and the inconvenience of having two ears. 

Mijo - measure and listen, not that difficult

you missed the essential point " rest of chain "

time and phase are just part of the magic since 1977.... 

The human ear brain processing can differentiate between the initial primary sound and the reflected sounds so long as there is enough time between those sounds. Something that microphones are challenged to do. Which is not to say that microphones and the measurements they gather are not important. Just the opposite. The vast majority of manufacturers of time coherent loudspeakers recommend pulling their loudspeakers out from nearby walls for this very reason. Those time coherent loudspeakers that are meant to be placed in, on or near the wall are designed with an understanding of the unique predictability of the affects of this proximity that would not otherwise be available with all the differing variables of users placement and variables of users rooms, and  compensation is built in accordingly.

@jjss49 , flat is always the best place to start.

not debating that point (starting point, reference point) - my statement refers to aiming for a perfectly flat measured speaker response as a sonic end point