Resolve issues with the Document Information Panel
In Office 2010 & 2013 DIP Panels, BCS fields display as Read Only fields. So for a new document generated through SharePoint 2010/2013, a user is unable to complete BCS fields in the Office app as other field types. The user will then be unable to check-in the document.
This is a major problem for adoption of BCS and is one of the major drawbacks.
In Office 2016 Preview, Document Information Panel has been removed completely, meaning the metadata is completely hidden from the end user. Also in this version of Office 2016 BCS fields are not displayed at all.
Metadata is very important to getting the most out of SharePoint, it is in Microsoft's best interests to make it as seamless as possible for an end user to enter and update metadata within the client application.