As such I think Sony should allow gamers to customize those colors instead of making users jump through hoops to get their favorite color.
As far as I know, there is no technical reason this thing exists. The lightbar on the DS4 had some purpose for the VR stuff I think? I don't see a reason why sony would not let me deactivate it on the DS5 though.
I don't believe this is the case. The colors show that. I might be wrong though! Just seems strange to have two things indicating the same thing. PS4 doesn't have one, two, three lights, it only has the different light bar colors.
Many games on PS4 changed the color of the light bar, either to correspond to events in the game, or (particularly in multiplayer games) to match the color or icon of a player's character or icon. I assume PS55 games will treat the lights on the DualSense in a similar manner.
Yes, it was used for VR. More specifically, it was used in conjunction with the PlayStation Camera, even before PSVR was available. The position, orientation, and color of the light bar could be "seen" by the PS Camera, and (along with gyro and accelerometer) would aid the system in locating players in motion-controlled games.
This would be useful for accessibility purposes. Color-blind players might be able to recognize that one ore more lights are glowing in certain locations on the controller, even if they are unable to discern the difference between the actual colors of the lights.