What is the usefulness of the analysis of accounting records for a secured credit 100% by collateral such as as investment?

Investor or a lender is more concerned on the cash flows the company can generate than the collateral coverage available to cover up the loan / investment. 

Secondly, the collateral value today may not be the same in the later period thus putting the coverage at risk. 

A lender / investor hence gives more value to the cash flow generation and debt servicing capability of the company than the amount of collateral cushion given at the time of lending / investment.