Advantages of SP Libraries over Folders:
Fewer Clicks
Permissions can be set at the site/library/folder/document
Templates
Workflows (can be isolated by library)
Versioning
Requiring Check-Out (security feature - helps to maintain integrity of documents)
Content Approval
Editing options w/i SharePoint
Use "Edit" - Edit w/ default program if MS Office file
If it is non-MS Office then navigate to the Windows Explorer view through your shortcute
Versioning
Content Approval
Adding Alerts
owners can add alerts for other users as well as themselves
Workflows (there are steps that need to take place in order for work to be completed)
Adding an "Approval" workflow
Adding multiple Approvers (approvals are sent in order by default)
Assigning a single task to group - only requires one user from group to approve