#1: Immediately useful. In order to become transformative, a technology needs to become widely adopted, which doesn't happen if it's not useful for something, right out of the box, that users aren't already doing. This can't just be a qualitative enhancement of things we do already; it must be something we cannot currently do at all.
#2: Economically scaleable. A transformative technology must become cheaper to use as more users come online. A technology that doesn't scale can't become widely used, no matter how useful it might be, simply because its use will remain out of reach of almost everyone.
#3: Game-changing/Historical. A transformative technology make possible later technologies, or unlock new activities with later iterations of the tech, and those changes should extend beyond the merely technical.#3 is the trickiest of the three to asses in a technology's early stages, but a good example would be the smartphone. Smartphones supercharged social media; when combined with the phones' cameras and large memories, smartphones made it possible to record, and even simultaneously upload, e.g. video of encounters between members of minority communities and the police. Consider how profoundly this has impacted the way we talk about law enforcement, or the way in which Mitt Romney's 47% video altered the outcome of that year's U.S. Presidential race, and you get an idea of the potential impact that we're talking about.
That's it; technologies that fulfill those three criteria can turn new tech into technological revolution. Given these three qualities, a new technology can alter the way our society does almost everything; without them, a new technology makes a brief splash and a small ripple, and then vanishes beneath the surface of history, never to be seen again.
Now, let's apply these criteria to an historical example: the telegraph.
#1: The ability to communicate over long distances has historically been game-changing; many events in history have hinged on whether (or not) a message got where it needed to go in time. Telegraphy allows you to send messages in minutes, rather than weeks or months, with little to no loss of information, the utility of which is obvious. PASS.
#2: The telegraph required wires to be run over long distances, and a source of electricity to power it all, so it was a matter of good timing that it was invented at the same time that steam power was also becoming a thing. Steam-powered trains also required long rail lines to be laid, and telegraph lines could be (and were) run along poles alongside them for comparatively little extra cost; and most of the electricity that we use is still generated using steam-driven turbines, which provides juice. All of this scaled well, and kept scaling, to such an extent that we're still using it all. PASS.
#3: The telegraph made it possible to send information long distances over wires and cables using binary encoding (dots and dashes), an ability which not only didn't exist previous, but which was so powerful that we're still using it. Replace dots and dashes with 0's and 1's, and add microcircuit-controlled switches, and routers, and you end up with the Internet. PASS.You can do the same exercise for radio, television, microcircuits, personal computers, the Internet, and the smartphone. You can't, however, successfully complete the same exercise for, say, 3DTVs - nobody needed or wanted them, there was little to no content for them, and they've already sunk without trace. VR is sinking now, for the same reasons.
Now, let's apply the three "transformative tech" criteria to the Internet of Things.
#1: The ability to control home appliances remotely is potentially useful. It's mostly party-trick usefulness, apart from thermostats and home security/surveillance systems, and being able to, say, check from the road whether you need milk, bread, or eggs isn't actually all that useful in a society that has convenience stores in every neighbourhood that sell milk, bread, and eggs, but it's still something, so it counts. PASS.
#2: The amount of Internet traffic that will be generated by IoT, and how to deal with that, are still question marks. ISPs claim to be having trouble keeping pace with the traffic increases caused by video streaming, and almost all of them are hiking the rates they charge for service to offset their extra costs of doing business; all of this gets worse, not better, if IoT becomes more common. FAIL.
#3: There's almost nothing in your home that you actually need to remotely monitor or control except for a) your thermostat, or b) your home security system. Programmable thermostats make "a" irrelevant to most users, and the ability of hackers to gain access to home security camera feeds and thus invade your privacy make "b" more problematic that it's worth for most users. Not only is there no consensus at to what best practices for IoT security or consumer privacy might look like, there's no guarantee that every IoT hardward vendor will comply with them, which makes them even less attractive.
Smart speakers are the canaries in the coal mine, here. Apple's HomePod is already struggling in sales; Facebook's late entry was delayed still further, mainly because the Orwellian nature of the devices makes a very poor match with their ongoing user privacy and data collection issues. Amazon's Alexa and Google's Home are duelling for the lead of the product category, but nobody will be talking about them five years from now, in exactly the same way that nobody much cares about tablets anymore. There's no sign that any other IoT category is finding wider popularity than smart speakers are.
No adoption = no impact. FAIL.The companies that make the devices have many reasons to want to monitor everything you do, and every product that you use, in your house... but there's little to no benefit for consumers. If you're wondering why IoT has been so slow to take off, in spite of being available for years already, the fact that it fails two of the three transformative tech criteria should point you in the direction of why.