I agree with you often; but you really are a terrible negotiator. The administration has made it amply clear, over several years, that the US prefers a negotiated resolution to end Iran's nuclear weapons program. The Iranians know what the parameters of such a resolution would look like. They have many channels for communicating a desire to reconsider their previous, multiple, decisions to forego serious negotiations. Trying "one more time to reach out to the Iranian leadership in order to avoid a military confrontation over Tehran's nuclear program" would only change Iran's understanding of the situation in one way: it would reinforce the hand of those in the Iranian government who think we are bluffing.
This conflict can be ended at any time, by them. But we all have to live with the fact that there may be no peaceful resolution, either because the Iranian government, for whatever reason, doesn't believe it's in their interests, or because they miscalculate. Reaching out now can only increase the chances that they miscalculate. So it seems to me pretty clear at this point the chances for a peaceful resolution are diminished, not enhanced, by further US squishiness. The only way forward that has any chance of avoiding a war is to ramp up pressure maximally, and quickly, in order to remove ambiguity about our intentions.
In a related development, Eli Lake doesn't really believe I believe what I wrote: He tweets (@elilake) that "I feel like @Goldberg3000 doesn't really think a last chance outreach to the Mullahs will actually work here."
I believe that the Obama Administration should make a sincere effort to present to Iran an alternative path, but I think the chances are slight that Iran will go down the path.