Hi Andy,
I strongly agree with you on that point, but there are things Moodle doesn't do (or do well), that Mambo does. While I know how to build in restrict access and activity completion conditions, and how to add badges as rewards, this is only a small portion of what one would like to do with a gamification approach to instructional design.
However, I'm open to suggestions on how to boost gamification possibilities in Moodle.