I would not say that it is completely useless I can e used to understand how the light you are shooting in and how it relates to how the sensor stores that data.
Take in day light if you are metering on something white most of the time you only have to worry about the green channel. It will also give you a better representation as to how the red channel relates to the other 2. If you are shooting say something red with very little green in the scene you may want to push your exposure to the right a little more. It really is understanding how your camera reacts to what light you are shooting at and how far to the right you want to push it