Comment by TeMPOraL

I think they are still a bit too expensive for people. You can either get a whole system for several dozen kUSD, or single elements (e.g. smart outlets) for ~$100 each. The former is a significant expense people might not want to pay at once when buying homes, and the latter is a bit too expensive to buy one by one, because you require to have at least few of those devices before the system starts to get useful.