Here's another arguement for the Production DBA (at least in an enterprise environment) - To act as a bridge between the Development group(s) and the System(s) groups. My past has always been both Systems Engineering and DB Administration. I've found that there is always a big divide between the two groups, and someone who knows a bit of both can really help. Stuff like designing storage (Raidsets, cloning, etc.) with the eventual file/filegroup design of the database in mind, etc.