This is a feature request that is critical for any mods that would like to easily implement persistence. Exposing information about players such as a Steam ID, an Xbox Live ID, or similar would enable modders to implement persistence-related functionality with minimum effort, as you could easily bind things to players and have said things "stick".

Use cases range from saving/persisting inventory/loadouts in/across servers to banning troublesome players. I would consider this a major feature from the scripting point of view.