Controller profiles are/were my stop gap measure to handle input rebinding (prior to OpenXR style inputs being implemented in the engine in 4.24) and controller re-orientation for grips (prior to OpenXR being the default interface in 4.27+).
Currently until removed, they provide a method of loading an offset transform based on the controller being used that lets you re-align the in game hand representation to the users controller, regardless of the controller being used.
Once OpenXR is default to the engine I will be deleting the templates default controller profiles, they will serve no technical purpose as under OpenXR the default tracking pose is the open palm of the hand so every controller should be aligned from its driver directly (assuming they are setup correctly) and input re-binding hasn’t been possible since 4.24 dropped. Controller profiles themselves will remain as a way for people to allow end users to customize offsets.