I kind of like the negative medals. Maybe it is because I have never betrayed anyone. I don't plan on betraying anyone either.
I have noticed a lot of people say the game is all about betrayal. The people who betray me always say that too. The ones who betray me have told me "it is not a kiddie game", "it is called subterfuge for a reason", and one guy just said "nothing personal" (I didn't mind that one so much actually)
Yes you can betray someone and it works out well in-game but the backstabber medal is well deserved and helps players like me not trust you.