The Nest Thermostat, for instance is about energy savings and not having to think too much about the thermostat. Lockitron about the convenience about never having to worry about keys again...
Saying this makes me feel old or something, but I just don't get it?
I had a friend with a cottage and they had a system hooked up to their AC. When they were leaving home to drive to the cottage, they would call the cottage phone number, the AC system would intercept the call and after a few buttons later (ex #485*) the AC would be up and running. By they time they arrived, the cottage was a cool 19C.
Home automation provides convenience (not having to drive all the way home to close the garage you accidentally left open), integration (being able to control and monitor your lighting, HVAC, sound, video, pool/spa, landscaping fountains/lights, etc. from a single remote with a single UI), and customization (pre-programmed actions, timed sequences, and unique designs that make a house uniquely suited to its occupants) that are not otherwise available.
Edit to add: there are also accessibility benefits to automation.
Most people won't want to monitor their lighting, HVAC, sound, video, pool/spa, landscaping fountains/lights, etc.
* Never coming home to a dark house (minimal lights automatically come on at sunset, and tapping one button immediately inside the entry door turns on several lights in the area you're walking in to).
* Watching a movie in complete darkness, but hitting 'pause' and having the necessary lights to get to the bathroom or kitchen come on (at a dim level so you're not suddenly blinded).
* Having "believable" automated operation of lights and other things when we're on vacation, giving a better appearance of someone being home.
* Being able to adjust the temperature when we're not home (helpful when we've been gone a while and want the house pre-warmed/cooled).
This certainly ALL falls into the luxury category, but it's quite nice. I don't think the issue in this market is that people who aren't geeks wouldn't enjoy the benefits. It's a combination of a lack of proper marketing, high cost, and the interfaces for these things not being where they need to be for average users. Maybe Apple can address at least some of those factors.
Garden automation (lighting, irrigation and monitoring).
Better window treatments like controlled awnings and blinds or window opacity in the future.
I've gotten much use out of a simple remote control dimmer  in the living room, but that's not automation, and most people would probably consider even something that simple as an unnecessary luxury, much less want whole-home automation.
The real power is that every item can be improved a little with automation. Your dryer starts an hour before you wake up so that your clothes are dry, your underwear is warm and toasty to face that cold winter's day. You can check from the supermarket if there was anything you don't have at home for the cake you're baking. The lights slowly dim to get your brain thinking it's ready for bed. Your lights change colour to make the room feel warmer or colder. The blinds slowly open just before you're supposed to wake up so that you can be woken by light rather than an alarm clock. Your oven begins cooking the roast to work around your schedule. Stopping the microwave from continuing to nuke the popcorn from the other room so you can wait for it to cool without getting up.
None of these are particularly brilliant and maybe you would look at it and ask why spend an extra thousand on a fridge for this? An extra 50 a light-bulb... A few thousand for installation of a base system just to have the privilege. Another 500 for motors for blinds. And each of those is just for one nice hardly noticeable difference in your day.
Maybe the cost for the value doesn't make sense. It won't for a lot of people. Having said that it seems to me that what we're talking about here is automating some of the duties of a butler/body servant type job, at a lower cost than employing one for something that will be in place longer.
I'll also add some good old anecdotal stuff at the end about some of the silly little contraptions I've found in my apartment in Japan and the difference they make. I've got an automatic bath tub push a button and it fills to an appropriate level at a temperature you set. It seems so silly to spend the money to save yourself two minutes of faffing about with taps for something you might do every other week or once a month. But without that two minutes and without the pressure to not let it overflow I have nice relaxing baths much more often because all I need to do is push a button and finish whatever I'm doing before grabbing a book.
There are also remotes for the lights. It's great to walk in the door grab the one remote and walk through the place turning on and off the lights on my way to the lounge to settle down all without having to go slightly off towards one wall or another, this seems small (or ridiculously lazy) but I honestly think I'll spend the money when I move to keep this tiny freedom. Being able to turn the lights on and off from bed and freely rearrange rooms without worrying about light-switches is an added bonus as well as dimming by remote are all great and have made ever day slightly more pleasant. There are a few other contrived convenience around (there are others that I was used to that are missing here though) and I can honestly say that quite a few of them are something that have made necessities slightly easier or enjoyable things more accessible. I'll definitely be hunting out these little conveniences when I've left. So there's my two cents.
Can we do that yet though? Some sort of smart inventory taking cabinet?
> The problem is it's a thousand little things not just one big thing.
Absolutely right. But we start with things that justify a purchase because they complete a worthwhile task on their own. That reduces the barrier to entry.
It's one of those things that would take a large amount of work for a company to get it to the point where the ease of use is the same as the current system, I'm sure we'll eventually see a usable system (as it seems that computer vision and object classification techniques being developed in other areas will be applicable here).