It's a good question, but the answer is, depressingly, simple. The bulk of humanity prefers single purpose tools. The tech field has a well known fondness for products with broad utility, but even then a lot of that is economics and finance disguised as consumer empowerment.
Take smartphones for example, or even tablets to a large extent. They aren't super customizable, extensible communications platforms with more computing power than I had in my first CAD workstation because the consumer wants that. Smartphones are those things because it's the only way mobile carriers can get you to pay 7-8x over voice service for all the full on data package that let's you watch porn and the Pope's Easter Sunday Mass simultaneously on split screens in the palm of your hand while having a voice call with your boss about the upcoming audit. Combining the Pope and porn, wirelessly, doesn't come cheap my friend.
You've got to develop an insanely convoluted, excessively low margin operation with huge reach and infrastructure and subsidize it all by giving ~200 companies per mobile account a couple of pennies each. Otherwise your Galaxy S4 would cost about the same as a trip to the ISS.
Everybody kind of accepts that, but look how hard all the carriers try to get their crap apps and software in your face so, maybe, they can share your money with 160 companies instead of 200. At scale, that's a lot of money.
But ideally, you want a single use device that gives its user absolute control over whatever you tie it to. It's a hell of a lot better for company putting out the device, and outside of the tech savvy minority, it's what consumers want as well. It's the same reason consolidated home entertainment system remotes have always been a hole that companies toss money into so the bosses imbecile son can run a project. I had a Texas Instruments calculator in the early 80's that could work my cable box and people thought I was a warlock, or a Russian spy. It hasn't changed one bit (maybe you'd be a terrorist, instead of a Russian spy).
Extensibility, modularity, cross compatibility, those things are, largely, what tech savvy folks think about, not the average consumer and people with scads of disposable income. The just love the idea of really expensive, single purpose things. They eat that shit up. They'll use stuff like that just because they can. It's just fantastic from a behavioral study standpoint. They're getting off by pressing a button that's charging them a premium for an activity they did yesterday that they didn't even consider the financial implications of. It's fabulous!
I'll close with this. I've taken to lurking in the Best Buy stores in the greater DC area and watching the people who buy those tiny little plumbed in 1-cup Kcup coffee makers that are inset into the wall of your house. You know what I'm talking about? The thing is $1,000-$2,000 depending on the model, and I'm assuming anyone who buys one isn't the sort to run plumbing and electric to an appliance they've framed into the wall themselves. Fair assumption? I'm trying to kind of classify the market for such things, simply to satisfy my curiosity. It's intriguing.
See, I've got plumbed in coffee makers in our office too. I get that. It's just easier and cleaner. But they're big ass commercial machines that you load with a No. 12 grain shovel and the coffee comes out into a big stainless steel bucket about the size of the propane tank on a fork truck and you fill up the insulated stainless carafes and take 18 cups back to your office at once. It's great, it's efficient, low waste, coffee in 50lb sacks is dirt cheap and the grounds make for way better traction in the snowy winter parking lot and the smell keeps the Canada Geese from shitting all over the campus. It's great! There's six of these things at the office, grand total was $6,500 installed and 50+ people drink designer coffee ground in our own design of bean grinder all day long, every day for about .22 cents a cup of $5.00 a bucket if that's your thing. Those shitty little things at Best Buy are more than 2x more expensive than your own coffee factory, waste is just insanel high, and you can't even fit a standard US size coffee mug in there, I tried.
The fact I have seen 18 of those machines sold at four stores over a 15(ish) month long period prove that this Amazon gadget will not only appeal to people, they'll use it to buy coffee for their shitty little coffee makers.
Holy shit! What Amazon really ought to do is have the standard, full feature model that retails for ($x), then have an an ad supported version with a big 'I'm feeling lucky!' button and something will be shipped right to your door. Genius!