Grant Potter: "Some gamers like to identify with the avatars they are controlling. It’s only natural to want to play the characters that appeal to us. Not everyone gets a sense of accomplishment by just beelining it for the most powerful individuals. Some of us need the aesthetics to help make our choices and character themes tend to appeal to us emotionally invested gamers more than visual design.
Before jumping in, I’d like to note that character themes tend to be featured more prominently in games with larger casts of playable characters. It’s more common to see them in JRPGs and fighting games than in adventure or platforming games, where the game is more about the experience than it is the individual’s achievements."