Simple, really. Lots of times when I am dead, I spectate a teammate with an awesome looking skin. I think it would be nice to know the what the loadout card is somewhere. Plus, more flaunting of high end cards may make me want to get one.
I’m not sure if people will like a card in their HUD every time they watch a teammate, though. Maybe if you hit H while spectating them brings up their loadout card?