Thanks for your feedback. I'd say you are the exception that proves the rule
But the general question remains: What's the best way to encourage people to contribute, not only to Moodle Docs? I admit that having or not having a sandbox is only a small part of the problem but should be taken into consideration.
Some more input:
"90-9-1 Theory"
* 90% of users are "lurkers" (i.e. they read or browse but don't contribute)
* 9% of users contribute from time to time, but other priorities dominate their time
* 1% of users participate very often and account for most of the contributions
(Source: http://www.wikipatterns.com/display/wikipatterns/90-9-1+Theory)
Originally taken from Jakob Nielsen's Alertbox, October 9, 2006:
"Participation Inequality: Encouraging More Users to Contribute"
http://www.useit.com/alertbox/participation_inequality.html
Cheers,
Frank