To me, demos are good for 2 things only. Testing if it works on my PC specs, and seeing if it's fun.
Since I don't play PC games much anymore, point 1 doesn't matter.
For point 2, I'll know if I had fun with only 1 small stage/mission. There's no need to give me 15-20% of the game for a price, it'll just lessen the experience with the full game.
And it just took away any remaining interest I had in buying C&C4.
Just checked and it got so many bad reviews. And the addition of necessary constant-online DRM checking, EA is just being stupid.
Next they might make games with only 640x480 resolution, and ask a price for unlocking higher resolutions or something.
It's so sad Bioware are stuck with such idiots. Otherwise I wouldn't even care.