Good question! Active x-overs/built-in amps are great!
Of course, the cost of those parts and the extra labor multiply into a higher retail. Existing powered-speaker companies offset some of that by using far less than the best woofer, tweeter, cabinet, wire, terminals, amplifier design and electronic parts, and via quick-assembly techniques- like push-on connectors to the drivers.
The powered monitors sound better than their competition, but this only reflects on how bad their competition is, and not on what can really be achieved with proper drivers, cabinets and passive crossovers for the same total cost, or less, including the outboard amplifier- which can be changed that day if it goes bad, as opposed to sending the powered speakers in for repair. Talk to a repair tech about the bright idea of building a VCR into a TV set. Makes them curse...
Home users would have to scrap their existing amplifier to use powered speakers- not likely.
Whose amplifier design do we put in, assuming they would even sell their "best design" to a speaker company? Rowland, Edge, Audio Note, 47Labs, Bryston, Wavelength, Manley... none are perfect. And they always get better (almost always) every year or two.
Those are the reasons which have kept us from putting in active electronics here.
Except for the compromised powered monitors out there, or cost-no-object reference speakers, we would seem to be stuck with passive crossovers.
Best,
Roy