I’m with Jamie on this one.
Having said that, I am going to defend the use of lights on two main points:
1) It’s called aesthetics. They may annoy you because you don’t know what they’re for, but you can hardly deny that they can look nice.
2) Britain is the gloomiest place on planet earth. I mean, I love it and everything, but you would be hard-pressed to argue that it is nicely lit for more than a few months a year.
In Canada, having oodles of snow means having zillions of light reflectors all over the ground. This makes for a beautifully-lit atmosphere all the time. Which is pretty good compensation for the fact that it is -30 degrees for 5 months of the year.
Here in the UK, we have… nothing. So, between the cloud cover, no street lighting (or if there is, its hardly-visible, soft orange glow is so widely-spaced that it’s border-line pointless), and grey streets, it makes for a very dark place.
Ergo, house lighting is nice.