What is the benefit of declaring bankruptcy and hiring a lawyer opposed to just not paying your credit and mortgage bills anymore?

Bankruptcy provides you with protection so that you won't be sued by your creditors.  If you quit paying and don't file bankruptcy, your creditors will sue you and after obtaining a judgment against you, they could obtain a wage garnishment to enforce the judgment against you.

Depending on your income and other factors, you may be eligible to file Chapter 7 bankruptcy.  Chapter 7 is straight liquidation which eliminates your debts.  If you are not eligible to file Chapter 7, you can file Chapter 13 bankruptcy.  Chapter 13 requires a plan (budget) for repayment of your creditors.