Also auto on/off. If you put Home Assistant app on your phone, you can wire up automations that turn things on and off depending on whether or not you're home. Could also have Home Assistant pull in air quality/pollution info for auto on/off. High pollen count today? Keep it running so I sleep well. Low pollen count? Turn it off.
Maintenance is minimal. I set the dehumidifer up 2 years ago and haven't touched it since or had a single issue. Main thing is a) get it working, b) get it isolated from internet, c) never touch or patch it.
Once the data is in Home Assistant, I can also look for correlation with wearable health info. Does purifier running improve sleep? Does changing thermostat set point improve sleep?
Setting up almost never takes more than a few seconds for me. I have Apple home, it’s almost always scan a QR code, wait a few seconds for wifi and done.
Also it’s fun to mess with.
What I like about IoT is the idea of hacking them :-). Of course I don't want connected devices running proprietary firmwares anywhere near my LAN.
Also one thing is that when a company sells an IoT device, maybe they mass produce it and it's cheap. Whereas if you wanted to build it yourself, it would be harder. Getting relatively good and cheap hardware and putting your own software on it is nice!
It is convenient to be able to monitor air quality from your phone, sourced from a device that is designed to improve it. Because then you can see how much of an impact it is actually making, move it to a different location with better airflow, etc.
I have the non-wifi version, and have to use a separate device for it.
One of the nice things about air purifiers, unlike owning a boat or leaving a stove on, is that its never going to surprise you in a bad way. You don't need to really monitor anything, it will just purify some air. Do you really want to be bringing that under the umbrella of the stuff you monitor? Maybe this is an irreconcilable difference and we cannot see it the other person's way.