Thanks to GamersWithJobs for their piece discussing early, bug-filled releases of videogame demos
(actual link here
, broken website referrals currently in effect.) The author points out that if the downloader "...doesn't like the demo, the player will probably skip the game which will hurt the publisher in the end. That makes me really wonder why some of them appear to insist on early trial versions."
He concurs that sometimes PC demos are 'leaked' from magazine cover-discs, but wonders "why such a poor representation of a product would be released anywhere in the first place"
, and concludes: "I tried to understand the reasons for the release of rather 'flawed' demos, but short term gains such as marketing deals or market timing are usually clearly outweighed by the overall consequences."