Have you ever been at the store and wondered if there was anything else you needed to replenish in your fridge? Wouldn't it be great to pull up a webcam view of the interior right at that moment? Or how about making sure your oven and stove and iron are off? Or getting a video call on your smartphone when someone rings your doorbell while you're not home?
These are just a few of the things that I personally would find useful or at least interesting - I'm sure other people have entirely different lists of things that would be useful or interesting to them. However, in order to allow all of us to do the things we want, we need to first connect, well, pretty much everything to the internet.
It needs to be well-planned and secure, of course... which is why I won't be installing any of this stuff unless I've vetted it myself first.