Personally I think developers unwilling to allow "try before you buy" as shady and not confident in their product. They'll gladly take your money even if people are unhappy about the quality or didn't get what they expected. If I did good work I'd offer it up gladly for people to try, although in a limited fashion so they have to buy it if they like it. Demos worked until the file sizes started getting a little absurd. But I still use them to this day. I tried a couple on my ps3 before I wanted to decide to fork out $60 for a game.