I mostly identify my soldiers by their callsigns, and I suspect most people do too; however, the callsigns only show when you're looking at the roster or in-combat. Many other times- in particular selections for many buildings, such as the AWC retraining slot- the game displays nothing but the soldier name and rank. It doesn't even show class. Is this a modding limitation, that you can't show this information in these other windows?
SUGGESTION: Honestly callsigns or soldier classes displayed in all menus would be a massive aid in remembering who the hell a certain soldier is, instead of players constantly having to exit and go check who's who in the armory.