Unless you get very fortunate with outlet locations, mains power is harder to put around a room than thinner/more discrete speaker cable which can be placed under rugs, along baseboards, behind drywall, etc. Also easily cut to exact lengths. AC mains is a different beast, subject to electrical code and a lot more permanent.
Wireless is also challenged by bandwidth/channel count, latency, and interference. In practice these are probably not issues for most setups, but they are considerations which make them less desirable to enthusiasts, and not a clear upgrade over passive. This is why I've advocated for PoE powered speakers, which retain some of the biggest benefits of passive (easy/discrete cable, effectively unlimited bandwidth). I'm not satisfied with the current landscape of PoE speaker options, nor the difficulties in getting a Dolby/DTS stream into this format, but I think if you were to throw out all convention and reimagine an "ideal" HT/multichannel setup it would resemble something like this.