What's the Dualshock 4 light for?

[The Antagonist]

Certain games use the light as a means of signaling changes in environment. For example, it changes to orange when you enter power armor in Fallout 4. In party games, the light tends to be your assigned color.

So it's basically useless. Like, I have to look at the color to know if I am inside the power armor since, you know, I couldn't tell otherwise.