This might get tl;dr. But. I tend to think of it in terms of real life. Like, not everyone is sociable, amicable, and fun to be around. Some people are miserable, or odd in ways that don't make them an "omg shiny beautiful speshul snowflake", despite how different they are. They might not get a lot of interaction, or whatever, but without them, you'd sort of have a game that was just a popularity contest, and that's not all that great. :|