Few things make information look more unappealing or unreliable than having a date set in the past credited to it, however recent that past may be. The Abundance theme always looks up-to-date and fresh, thanks to the Javascript clock in the top corner of every page, and by default uses no dates on posts in order to avoid giving them an antiquated look two weeks after publication.
If you’d prefer to put a date to your posts, this is a simple matter of ticking a box on the theme options page.