I see what you were saying about context now. Sorry.
(1) I'm not aware of anyone who suggested that no investigation was needed. We had an investigation into this, the same as we have an investigation into any incident where government personnel are killed on the job. What's unusual, in this case, is that we've had such lengthy and repeated hearings about it, and that new efforts continue to pop up, so long after the fact. It's also unusual how much of the attention has focused on the trivial side show of how the administration spun the incident in the first couple weeks after it happened, rather than the more fundamental issue of what lessons can be learned from the incident to make our facilities more secure in the future.
(2) I'm unaware of any bogus cover story here. Are you referring to the initial CIA talking points that suggested the attack might have been inspired by the Cairo demonstrations, which in turn were related to the anti-Muslim video? If so, in what sense did those talking points end up mattering? I mean, the "hit," whether it was positive or negative, was already a fait accompli, by that point. Nobody hid the fact the attack had happened and that four people had died in it. Susan Rice was open about the fact that the attackers had been heavily armed and that the administration was looking into whether they were al Qaeda affiliated. I honestly don't get why Republican think it was highly important whether or not there was a demonstration occurring at the time or not. Can you explain that to me?
Anyway, my take on it is the Republicans have fixated on the trivial aspect of the story (immaterial details about the allegedly knowingly false idea that there were demonstrations related to the anti-Muslim videos), rather than the issue you'd normally expect to be front and center (what can we learn from this to make facilities safer in the future), because they come at it from the perspective of wanting a cudgel to use against Obama and Clinton. They'd hate to get sidetracked into something substantive like improving security for our overseas missions, which might require higher spending. So they stick to the stuff where they can make the story all about the alleged dishonesty of the administration.