On the subject of obsolete ways of making light, I really miss the aesthetic of the yellow low-pressure sodium lights we used to use outdoors in the UK that ate the colours out of everything. They were actually about as efficient as LEDs in terms of turning electricity into visible light but didn't last as long and eventually the last European company making them packed it in so we've more or less switched over entirely at this point. I don't really like how a lot of modern lighting tries to make night look like day, I prefer the night to look like night!

There's no reason you couldn't have monochromatic LEDs in the same colour, part of me wishes we went for that instead of white ones which are usually pretty cold and harsh though they've got a lot better on that front with the really warm white ones being quite nice.