We only had 2 Demofests so far but I love the variety in demo types. We had demos with simple play time restrictions, demos with disabled features, sometimes even full games which is basically an early access play test for free. Also the progress on reacurring games is clearly visible. I agree that some demos have had more effort pit into them than others. Since I assume participation is voluntary, it's up to the devs to use that pressure for productivity, which is a legitimate motivator for some people.