Where IoT really comes into it's own is either doing stuff automatically or doing stuff without requiring my presence (remotely). By far my favorite application of this so far has been the ability to turn my air conditioning on or off remotely, that way I can turn it on about an hour or two before coming home to a comfortably cool room. This increases my quality of life without increasing my electricity bill too much. Other things like opening the blinds in the morning a bit before my alarm and either disabling or lowering the volume of my doorbell are pretty good too. Other useful for me applications (that I'm in the process of implementing) would include monitoring water levels, flow, temperature and pressure to control pumps, heaters (I don't use hot water during the day so turning off the heater would make sense until I'm ready to go to bed, for example), detecting leaks and maybe automatically shutting the water/gas supply. Things like automatically watering the garden if needed, smart reminders (remind me to do something only if I forgot about it, keep silent if I already did it), home security (doors, cameras, alarms), etc. are also things that would benefit from IoT integration.
The problem I have right now with most things IoT is that a lot of them are doing their own thing, connecting to their own servers, using their own apps, have different behaviors in the event of power outage and who knows if they'll continue working after the company moves on to newer products, goes bankrupt or gets sold. A lot of modern things you can buy are also pretty trivial in their functionality and don't offer much their regular, manual counterparts. This results in a lot of expensive hardware that's tedious to interact with for little benefit. Someone who actually wants to get a lot out of their smart things (like me), in the current world, can't really go buy off the shelf solutions or even pay someone else to design a solution for them, they have to be technically competent so they can hack existing stuff together, make their own smart things, fix stuff that breaks or stops working, etc. Smart homes are still pretty much the realm of the DIY hobbyist, there's little on the market today that can compete with what a halfway competent hobbyist with some time and money on their hands can cobble together for themselves, particularly with the prevalence of cheap and easy to use hardware platforms (NodeMCU, Arduino, RPi), open source projects in the sphere, cheap and widely available sensors and actuators, good community support, etc.
If IoT wants to move away from the current status as expensive, unreliable gimmicks, companies need to stop focusing on the idea of separate smart things and start thinking in terms of smart homes (like the kind we used to see in old sci-fi talking about the futuristic year 2000). There has always been a push in that direction, but it's never been too successful. What needs to happen is that people need to drop the idea of smart things as hardware and start thinking of them as peripherals. Just like your house now has a breaker panel, a hypothetical smart home should have a house computer, running a "House OS" to which all kinds of sensors, actuators and devices can connect through a universal house bus, pretty much the same way you connect a mouse or a camera to your computer today. This would let device makers focus on their devices and the "House OS" maker focus on other issues like remote access, scriptability, security, etc. When I buy a mouse I'm not worried about it working with my computer, I'm not worried that it'll stop working if Logitech goes out of business, I don't need to worry about it catching malware and DDoSing some website or phoning home with all my mousing data. Why should it be any different if I buy a smart light bulb or a smart air conditioner?
There are numerous projects working in that direction like this one from Mozilla, HomeKit and whatever else, and DIY solutions almost always have a centralized home server for all that stuff too, so I think we will eventually get there, but for now the modern smart home feels very similar to the way the earliest micro computers were in the late 70s and early 80s.