Multiplayer demos tend to have far more replayability than single-player demos.
Well the UT2004 demo is actually both single-player and multiplayer due to the game's included bots. It's not just an online or multiplayer experience, and it definitely hurt the full version's sales although the game still sold well.
If a player really enjoys a single player demo, there's a very good chance he'll buy the full version so he can access more areas, meet more characters, use more weapons and vehicles and just take in more of the story.
I agree, and you can certainly see that in demos from developers like Monolith. However in cases where creating a demo version of a game is cost or time prohibitive, a time-limited trial version of the full game or better yet a refund policy on the full game would certainly be a doable substitute for the developer/publisher and a desirable one for the consumer.
This comment was edited on Jul 13, 00:22.