They changed the content of a demo, not the content of the game. I'm pretty sure they would get shit for the rest of the development cycle if they didn't include battles and just put driving.
It's not like everyone is Toriyama there...
Considering they are selling this demo for money, you would think it would be more representative of the final game. It always sounded like there would be both and now it's removed. I can understand if it just wasn't ready, but they should have said so instead of making some excuse that fans would think it was a FF driving game.