What Hakre is talking about is actually something Drupal is doing to great aplomb and that I expect to see more in Drupal 7, that is, installation profiles. And I agree that it's a great idea. I think keep your default package as is, but als let people put together installation profiles that include certain olivine or additions as they see fit. If you wanted to keep some sense of control, require the use of core plugins. I know a lot of this stuff was done in the MU era, but it hasn't taken off in standard Wp installs. It could defnitely be a good thing for getting people more setup out of the box.