I suppose sound bars qualify as powered speakers but most of them still sound crappy.
Let's face it. Convenience and aesthetics is a driving factor in consumer electronics, second to price. It is much easier to run speaker wire than to have electrical outlets at every speaker location, especially in a remodel (as opposed to new construction). Powered speakers may make sense for a 2 or 4 channel setup but would it really scale nicely to 15 channels? You still need to get the source material to the speakers so will home owners run cat6/audio-cable and hydro to every speaker location? What about in-ceiling and in-walls? Will manufacturers offer powered in-walls?
Others have mentioned moving the amps external to the speaker box, and for a 2-way speaker system that could work since running 4 conductor wire to each speaker is not that big a requirement. You still need to decide how many separate amps and DSP units are practical. Cram them into one unit like an AVR or force people to invest in racks to hold multiple units? Equipment racks are for enthusiasts and those that have the cash to use an equipment closet that is out of sight. That is not the realm of the general consumer market.
As wireless audio improves I think the signal cable will eventually go away and Dolby will eventually reach a limit with how many effects speakers people will bother to install but AVRs will continue to rule simply out of convenience and the ease & low cost of running speaker wire. Sigberg's speakers could make a great front stage for a music and theatre setup and I could see a hybrid model with powered speakers in the front and passives for the effect channels, but I don't see 15 channel systems moving to all powered speakers any time soon. Most of the power is needed in the front 3 channels, so if you use powered speakers in the front then the demands on the power supply and amps for the remaining channels are reduced significantly. That hybrid model would yield the improved accuracy in the front where it is needed but still allow the convenience and cost savings of an AVR for effects channels.