You are perfectly entitled to let the court-appointed defense counsel represent
your case, and for that matter, you can even choose to represent yourself.
The primary reason you should hire private representation, however, has
to do with the fact that most of the defense attorneys who are available
through court appointment are tremendously overworked and typically do
not have anywhere near the amount of time available to properly investigate
the case, let alone to meet with you in person and maintain contact throughout
the process. If you are serious about achieving the best possible results
in your case, it is in your best interests to hire a civilian
who has the necessary time and resources available to effectively fight for you.