1) It's cool, trendy tech and people like that.
2) It feels like it's progressive and better for the environment, and humans are far more emotional than they are rational.
3) It's straight up cheaper to own from a fuel expense standpoint.
4) It will be very quiet/smooth.
5) This same technology can be put into all of GMs BOF trucks and SUVs, which is going to quickly become a competitive market.
You're splitting hairs over the real world effectiveness of one reason, when really very few people are going to care about that.