Given that the great majority of items requiring to be plugged into a socket are generally used higher up that the floor - computers, radios, TVs, stereo sets, Satellite, electric clock radios, etc. I think it would make more sense to set an "optimum" level for sockets, say 1000mm or thereabouts. Low sockets as someone has already pointed out are difficult for not only the elderly but also anyone with a mobility issue - I for example recently tore all the ligaments in one knee and you would not imagine what an impact that has for reaching down and bending over even now some three months afterwards.
Higher level sockets would also remove the problems with small children poking things in.
Assuming also that the cables are run in the ceiling void there would also financial savings to be gained as well as associated environmental benefits.
Just me or do others agree ?