"Who cares about having a "light show" in their house?"
People do - "mood lighting" is already a thing, that is why we have dimmers on some light switches now. Going further than that we can change lighting color, create patterns etc.
Many people, including myself and my kids, would LOVE to have that in their houses.
But only if it was easy, it needs to come essentially for nothing, ie, to be builtin from the start.
"What does that even have to do with the internet?"
Internet Of Things I have always understood to mean "Things that we can talk to and control using our devices, possibly over the internet" but in terms of the internet as it is widely understood, not much really. I am not sure I understand the question?
"We already have huge televisions that aren't very expensive. If we want the whole wall to be a TV, we can get a projector. A wall covered in individually-addressable LEDs is probably not going to be cheaper than a wall covered in televisions or just a big projector."
Right, and who knows whether that specific leap of imagination is realistic, I certainly do not - but I was not trying to make you want a TV in your wall, or even arguing that it specifically was a good idea, it was merely one possible example to make a point.
"The question the parent was asking was "Why hasn't anyone shown me a concept that makes me think, 'Now I want an internet of things in MY house!'?"
Yes. and I was attempting to suggest that one possible reason is that our imagination is balking because we keep looking at what we have in our houses now - all of which is extremely functional and works fine according to our expectations and desires, which have been moulded by what is available and by what has always been available.
ie, we are looking at our existing house infrastructure, the idea of an IoT and saying "but the Internet Of Things is not going to give me a faster horse, so why would I want it?".
I think I am doing a bad job of explaining myself, so I will bow out :)