As a design and new product development consultant
and having worked throught the concept for street lighting and with home IR .... I know that really good ideas often appear too obvious, trivial and supefluous at first sight. One has to be prepared to suspend disbelief the first time one encounters them!
It took me to work through all the way to the final picture..... But then "Illumination"!
Yes ... retrofitting cables in working commercial and domestic environments is a major disincentive... The "synegy" of "eop" (Ethernet Over Power - which as a radio ham I deplore) & multiband broad spectrum "luminaires"
may well be the "way to go". (.. for the local domestic / shop / office loop at least).
(founder of the www community wlan movement)