Do you get such pushback over the need for MFA, or more generally for the use of roles, or something else?
MFA seems like an essential defense-in-depth measure to ensure that a compromise of the locally held IAM key is not enough on its own to compromise your AWS account.
MFA seems like an essential defense-in-depth measure to ensure that a compromise of the locally held IAM key is not enough on its own to compromise your AWS account.