If they had cast Chris Hemsworth as Jack, they would have so much more earnings its crazy. And a lot more female audience. Oh so much more.
Man is 6'3.
Built like a tank.
He's 29 years old.
Can act and is much more popular with younger audience, then that joke of Tom Cruise.
Body images (some nudity, SFW though)
People know him from his roles of Thor or Huntsmen. They might as well met Jack Reacher through him instead of that Tom character