For a more gmail focused crowd there is the excellent Gmvault to consider: http://gmvault.org/
I'm not sure who are the people who can't use the above solutions and yet understand what IMAP is and that backups are desirable AND be willing to spend $15 for a Mac App Store app. Food for thought.
I switched to CloudPull ($10) from http://goldenhillsoftware.com and it's by far the best Google backup tool I've found.
It supports Gmail, Google Contacts, Google Calendar, Google Drive/Docs, and Google Reader. The app backs up a max of 10 accounts in the background and all the data is available in standard file formats.
Currently, looking at the support requests, people who buy it are not quite tech savvy but want to backup their emails from corporate IMAP accounts. Plus, I think the technical barrier is still quite low (select gmail/yahoo, you're done).