Creating roles in the AWS Identity and Access Management (IAM) with cross-account access permissions allows developers to assume those roles from their own account. This approach adheres to the best security practices by avoiding the creation of individual user accounts in each environment and adheres to the principle of least privilege. Making separate accounts for each role or only modifying the existing permissions in the production account do not provide the granularity and control over access to the different environments as effectively as cross-account roles. Applying MFA requirement is a security best practice but not sufficient on its own to provide the necessary cross-account access to resources.