This is very simple to me. Questions around the lack of security at the location are reasonable questions to ask and may help prevent such future occurrences by creating safety protocols that are more closely followed by those in the field. That is a proper use of resources and was already completed with a host or recommendations that the Sec of State has agreed should be implemented. Could they have done better? Yes. Were they negligent? I have not seen anything that suggests they were negligent and every attempt to prove they were has been based on conjecture and refuted by facts.
Questions about who knew what, when, and how they communicated that information are entirely political and serve no purpose other than an attempt to discredit the white house. They are an enormous waste of time and resources and are without any useful purpose. There was no scandal, there is no smoking gun. There is no treason. The bill for this circus should be paid by the GOP.