Is it Ever Too Late for Second Chances? Pesach Sheini: A Case Study

What is it about Pesach Sheni that is intrinsically connected to the principle that the Torah is not in chronological order? Why does the Gemara use it as proof when there are other examples?

Why was the fact that they didn't bring the Korban Pesach in the desert a disgrace - they weren't commanded to do so?

Delivered live at Torah New York, April 29th, 2018.