If there were something truly compelling about smart homes, more people would adopt it, and there would be more innovation in connecting up the various pieces. I suspect it might compel manufacturers to get on the same page. Compare it to the way browser makers push and pull on browser standards, until they eventually reach a rough equilibrium, because everybody wants their web page to work on every browser.
Smart home products all have their uses, but they all feel like minor improvements at best. I suppose it might be nice to have my house hook up to my phone and say "He'll be home in 45 minutes, so let's start warming it up now, and turn on the front hall lights when he parks".
But I'll be honest that I just dread the idea of trying to control a light bulb with an app. I really looked into that, because I've got a bedside lamp that can be controlled from a wall switch, and a common pattern is "shut it off at the lamp, wake up, leave during daytime, find the wall switch doesn't work". But the option is either pulling out my phone, or walking over and turning it on by hand. Even the negligible effort of using my phone seems like too much compared to the $0 alternative.
That's just a trivial personal example, but it illustrates why I think the smart home idea just isn't compelling enough to produce the vast sum of money that would allow manufacturers to innovate without trying to squeeze out profits from every aspect. Maybe somebody will find the killer app at some point, but in the meantime it feels like (yet another) solution in search of a problem, and doing so in a way that irritates even those who feel it can solve their problem.