I was a very vocal opponent for the removal of "include" from the process, but it was explained to me and I tend to agree with the logic based on the premise that OneCare backs up files by type.
1. Select the files you wish to backup by type.
2. Select any locations you wish to exclude from the plan.
The old "include" function ignored the files by type and actually caused all files within an added location to backed up and this caused confusion, though it was a nice back door method to get files that were originally excluded into your backup.
-steve