Craig s mullins has written an excellent book about who or wjhat is a dba check out an excerpt...
http://www.dbazine.com/dba_1.html

I personally think that being dba is entirely upto you. Some dba's can make developers sh*t and others can give it a rahter bad name by like pando said someone who does nothing and costs money.
Well you gotta show all what you can do , but it's also dependent upon how is it politically allowed within your environment without burning edges here and there.

Example:
When i joined this firm the db's were running on no arch log mode with no record of backups anywhere. Well that was being done by a dba who was doing it remotely by a "hi-fi oracle partner" shop. I'd say you had a peasant sitting on the throne.

Such retards make a dba job look so darn easy and then they get fired/ or leave and the next dba(who'd do a great job) can clean up his trash and be treated like trash.

So be a dba or don't, don't just mess around with the job profile, the reverberations(good and bad) go beyond your imaginations.

Tarry