The problem isn’t that Microsoft has no sense of humor, it’s that they have a very poor sense of humor.
By personifying Gmail as a personal email-reading jackass, they’re essentially portraying Google as both evil and corrupt.
It’s like trying to poke fun at someone in a fun, light-hearted way, then repeatedly calling them Hitler. “Oh that Tommy, he’s so naughty, he’s such a little Hitler”.
I would love to see Microsoft run such an ad on television. Two things would happen: 1) Google would probably sue them. 2) No one would stop using Gmail, they’d just think Microsoft makes really lame ads.
Win the customers by creating the best product, not by fear mongering.