DSpace's current implementation of Dublin Core was a subset or simplified version of the Dublin Core standard created by OCLC. Since the first release of DSpace, Dublin Core has undergone major revisions. DC version 1.1 was implemented in 2007 with 15 base elements a subset of the larger DCMI. Some users are currently misusing the DC standards, or lack knowledge how to use it properly due to the age of the current element set and the descriptions contained therein.
I recommend that the DSpace Developers look at using the full implementation of DCMI for the next major release after 1.6. Additionally tools will need to be provided for conversion of existing DC Metadata Schema.
Also, it would be advantageous to build into the software a validation of DC elements in a stricter sense than is now being used.