San Diego County has a great public defender’s office if you are indigent (i.e. you cannot afford a lawyer). However, even if you do financially qualify for a free lawyer through the public defender’s office, you likely won’t have access to that lawyer before the case begins. This can be problematic because, sometimes, what happens while a case is being investigated (before any court date is even generated) can be very critical to the trajectory of the case and in turn, your future.
Another consideration is that you cannot choose which (free) lawyer represents you. The relationship you have with your criminal defense lawyer is an important one. The communication style and expectations have to be aligned. Hiring your own lawyer gives you the power to choose and make sure that your future is in the hands of a person and criminal defense team that you select.