Time coherence - how important and what speakers?

So why is audio staying in the dark ages with passive crossovers? Even a listen to Mackie HR624 active monitors?Shows what active croosovers are capable of. Something to do with not being able to pick your own power amp?
I will admit that passive ATC 10's with ATC $3,500 integrated may have sounded better than active 10's with built in ~$500 amps so the power amp must be very good to see the improvement. Obviously a single $3,500 could be better than 4) $125 amps and this could explain why.

Good points Roy, Thanks. Keeping phase coherence sounds liek a good idea but I had a couple of novice questions on phase coherence, if you have a chance to answer. I don't think they were answered above.
- Is time / phase coherence maintained through the whole recording / playback process so the speaker is the only thing messing up phase and time coherence?
- What if a driver naturally rolls off greater than 1st order. Does the crossover have to boost the driver? Is this bad?
- Would the extra power handling of the voice coils in 1st order x-over degrade performance in other ways like higher inductance, mass, and hysteresis?

Revel literature is interesting:
"The crossover networks . . . maintain a 24db per octave, 4th order acoustic response . . . the steep filter slopes ensure good acoustical behavior in the crossover regions, with a minimum of acoustical interference, along with low distortion and wide dynamic range.
The somewhat steep 24dB per octave slopes also provide the benefits of keeping ALL DRIVERS IN PHASE AT THE CROSSOVER POINTS - A BENEFIT SOUGHT IN THE MORE COMMONLY USED 6dB per octave crossover designs from other companies. The steeper fourth order slopes, however, avoid the power handling problems associated with first order crossover networks."

Between Revels claim of maintaining phase coherence with 4th order x-over and comments made above about bad in-room frequency response (some Revel is very good at) with slow roll-off x-over design 4th order sounds very convincing.

Roy, that's okay to dominate the thread, I think we are all learning a lot. At least I am. One note though. Thiel speakers uses metal drivers and are first order (time coherent?).
Would a single driver be better still than 1st order crossover? I've got a 5" single driver speaker for a week. But it has a plastic "whizzer cone" glued on it. So I'm not sure if this counts as a true crossoverless design. Maybe mechanical, not electrical. Female vocals with acoustic instruments sound very different than my 4th order speakers. There seems to be more ambience to the music. But for some reason the single driver speakers don't have the pinpoint imaging.

NSM, Role Audio, and maybe Jordan single driver speakers are time and phase coherent.
NSM states "Time coherent" at their website here:
NSM

Any comments Roy?

So I guess I should pass over the NSM because the drivers are too close together? I'm not surprised they aren't time coherent.
I guess this is the A-A thread;
Roy's comments on Jordan

Jordan driver speakers now don't sound like they are worth the $1,500 after reading about their limitations.

Well, Roy could use some dealers so we could hear before we buy. I don't understand the resistance in that area.