You're probably right, but I was only a casual follower of the game. I'm sure there are others like me, but there are others like you that followed it more closely.
I'm just of the group that watched the video and read the pitch.
I believe that it was clarified in the FAQ that this was going to be a 3D (or 2.5D) game. A lot of people missed this and pledged without actually reading the description. When first video footage was released, there were a few upset people on GAF.
As far as I'm concerned, that's the backer's fault. It's the backer's responsibility to full research a project and read everything on the backer page before committing their money to a project.
I thought the concept art was pretty obviously not representative of the final game.