Because we are lazy, and everyone hopes it will help us become even lazier.

Yeah, and I remember in the early 90's a lot of people asking me "But why would you want to carry a phone with you all the time?"

I believe this is not a very fair comparison to connecting things to the Internet. When people in the 90s question whether they needed a phone all the time, they were questioning the usefulness of doing so. In contrast, connecting things to the Internet exposes the user to an additional vector of attack and exploitation (crappy or non-existent security from manufacturers, adtech companies selling your data etc). So the question changes from "what convenience is there" to "why would you put yourself to such a risk?"

Mobile phones always had a clear core market who genuinely had an answer to that question, even when the phones were so heavy they were 'carphones'. The market expanded as cost and weight went down.

The categories of home IoT device that seem to have a good answer are the fitness sensors and security systems. The smart kitchen on the other hand is probably doomed to be a bad idea.