I know i'm coming in late, but we use the colored lights for notifications and often get the question of why don't you just send a text?
Colored light notifications are persistent, unobtrusive, and universal.
For example, there is a light in the entryway and a light in my housemate's room that turn blue when I come through the front gate. I then turn them off again by voice once I'm in the house.
The blue light causes several things to happen.
One) my service dog (who can recognize a blue light) goes to the front door and waits by the window. He opens the door for me when I arrive.
2) if the blue light hasn't gone off after a few minutes, my housemate knows that I am stuck in the front yard and comes to help me (I'm in a wheelchair)
So why is this better than a text? Well, we found out from experience that when my housemate is playing video games he ignores text messages for quite a while. Or, he glances at it, goes back to playing, and forgets about it.
At the same time, the light going blue doesn't interfere with his gameplay, so he can just keep playing while he waits to see if the light is going to go off again.
The universality feature is obvious: my dog is talented, but he doesn't have a phone. Any notification that would be useful for people in the house who either don't have smart phones or are temporary visitors Will work better with a signal light than with a text system.
For things like the mail is here or the laundry is done, a lot of people find value in a persistent notification. They aren't necessarily going to act on the notification immediately. The light serves as a reminder where a text message does not.
There are still many use cases where a text message is better than a light, particularly if you want to get notification when you yourself are out in the yard or in a different room or away from the house altogether.
But a light notification is better for other cases, particularly those that require persistence or universality (anyone in the room is aware of the notification).
And of course there are other use cases where people will prefer audio alerts. And somewhere they will use a combination of these methods. Just depends on the details of each problem that needs solving.
In our case, we had a text messaging system that just wasn't working. Switching to a colored light solved the issue for that particular use case.