I think that an additional trait of a good DBA is to know as much about the applications that use the databases as possible.  In my estimatation this is huge, to be able to make proper decisions on how to resolve problems, what the proper backup schedule is, even how a particular table is used, etc...

A lot of organizations shelter DBAs from the programmers and make them inaccessible, even put them in a different room or building or farm out the work to a services group that know nothing about what they are supporting.  I think this is a bad idea.  Unless you have so many of them that you have them organized into DEV dba and PROD dba groups where it is the DEV dba's responsibility to interface more with the applications and be the liason with the PROD dba.

I have found it invaluable having been a programmer and rising up thru the ranks to be a DBA.  Just my two cents.