For one, I don't see anyone using them. I've never seen anyone use Siri on a phone, with one exception: I have a friend who uses voice transcription to write emails and text messages. (Not sure if that counts as Siri.) I don't know anyone who uses speakers such as Amazon Echo or Google Home, or mentions wanting them. I've used Siri on my phone a few times to try out silly things like asking about the weather or converting units, but it's seems so obviously bad that I've never tried going "Siri first". It's on my Apple TV, but I've not used it. Are people actually using this stuff as much as this article (and all the current focus on AI-powered speakers etc.) implies?
I'd love true AI -- a personal assistant that actually understood me, knew my tastes, remembered my choices and so on -- but that doesn't exist. So we get an uncanny valley where speaking to a device comes with uncertainty about whether the device will actually be able to service the request (see the numerous annoyed threads on Reddit about Siri not understanding incredibly basic things), requiring the user to carry around with them a mental model of the receiver's inadequacies. And we get that problem where many tasks that would be super useful to have done by an assistant is actually too difficult for a current AI. For example, booking a trip. I've never booked a flight that didn't involve pouring over pages of results, weighing the various compromises (optimizing for price vs departure time vs airport distance vs layovers vs airline crappiness etc.) and of course filling in a whole lot of information about myself. Let alone booking holidays (I spend many days on research for such a task). Bus and train tickets -- maybe, if it's a simple route with few variables. Dinner reservations and movie tickets, sure. Home automation, well. Once a home is fully outfitted with all lights, doors etc. being connected to a home automation system -- maybe. None of this is automated in my apartment, and I've never seen a home that is set up like this.
There's also the inherent limited utility that comes with an AI being unintelligent. For example, my Apple TV. I rarely know what I want to watch. To only rarely would I be able to say "Siri, play The Grand Budapest Hotel". Usually it would have to be something like "Siri, list me some sci-fi movies". But then I would still have to navigate the results. If it could respond to "Siri, show me French movies with an IMDb score of 7.0 or higher, or with a four-star review from Roger Ebert, that came out after 1990", well, now I'm interested. But somehow I doubt that those sort of multi-dimensional cross-referencing mechanics are currently available.
Edit: With the comments saying how good Google Assistant is compared to Siri, I tried it out. My first queries failed ("What is the weather in Washington State like in March") because it thought I was finished speaking and cut me off at "What is the weather", and showed me today's weather in my city. After a few attempts I got results, but then it returned Fahrenheit units (my phone is set to use metric/international units), and then it continued giving me Fahrenheit after I changed it, because apparently climate information is a "web search" returning text, not data: https://imgur.com/gallery/LI8Sc. Not so impressive. Meanwhile, Siri on the phone doesn't understand the query at all, ignoring the "in March" part and giving me today's weather, no matter how I phrase the question.
I can see a future where AI voice control is incredible, but it requires an enormous advance, and it seems like even the best AI of today just comes with frustration and failure. That's surely why companies like Apple and Google are working on this, but it doesn't explain, to me, why the current voice AI is being pushed so hard.