I was worried about this myself.
I believe it's only because they had only put the easiest missions in the demo and that is typically what you find in most demos.
I know there are different types of modes(arcade, real, sim) we can play from, but is there going to be more campaign options besides Difficulty and Lives?
I will more likely be caught shooting down noobs in multiplayer then playing the missions anyway. I'm getting a Dazzle DVD recorder for my Xbox so I plan on making short movies of IL2 soon on YouTube.