I think the blue is still considered "cool" perhaps precisely because it's rare and it was the last LED colour to be available cheaply. It seems to be a rather

I think the blue is still considered "cool" perhaps precisely because it's rare and it was the last LED colour to be available cheaply. It seems to be a rather persistent trend, though. In the UK a blue light on an electric kettle has been standard for the past 15 years at this point. Red/orange and green seem deeply uncool as they are associated with neons and old LEDs that have been available basically forever at this point.