It actually is, if done right. But doing it right means you have to do things properly and care about doing them properly. In general data collection about various things can be useful, from optimizing energy consumption of your home to making your own life a tiny bit easier.

The problem is, manufacturers saw the potential and rushed in to be the first on the market and forgot that online things need maintenance and patching. Goes to show how selfless the admin job is. As long as things keep working properly no one even knows they exist.

I have wifi cameras which were never allowed online from first second they were connected to my network. But on the other hand I have few air filters that I do allow to send data so I can contribute to global statistics on air quality and similar.