OP asks a really really good question though.. (And really important for M:BG)
Most of my friends are 30+
Today they told me.. have you seen the new trailer for a new wolfenstein game? Looks awesome! I'm like..
................ Trying to pretend I'm interested. Those nubs will never understand.
Other friends, gamers, I've tried to get to try MB or cRPG are just pussies who get turned off by multiplayer. For me, this is the best, most addicting game I've ever played. The intense, personal fights, the recognition of yourself and other players!! Package delivers actual physical adrenaline, real rage, both in large doses. No other game does this. (Enlighten me if I'm wrong pls. )
Anyway, as my friends are not much of gamers, IDK how to explain it. Usually wrap it in some funny story about knights and ninjas, with a fitting dose of self-irony.