Final answer:
The value-focused manager was terminated to help the firm reduce costs, as mature firms often seek to optimize efficiency and cut expenses when they have established financial strategies and expect future profits.
Step-by-step explanation:
The reason for terminating one of the value-focused managers was to reduce costs. As organizations develop, they often look for ways to streamline operations and cut expenses when their financial strategies are set and predictable profits are on the horizon. The relevant details in the scenario provided suggest that, as a firm becomes established and outside investors such as bondholders and shareholders become more comfortable providing financial capital, certain internal cost-cutting measures, such as management downsizing, might be taken to ensure the firm's competitiveness and profitability.