Perhaps the problem is that the demo is a true reflection of the quality of the final game, i.e a buggy, rushed, unfinished mess.
Without a demo, people have to BUY the game to realise what a complete pile of S**T it is, which sums up the modern game industry quite well - SO long as you buy the game, we (the publisher) don't care whether its any good or not.
I don't recall Aliens Colonial Marines having a demo.
Ozias' comments