Why do we call it 9/11?

Despite all the attention given to remembering the al-Qaeda attacks of September 11, 2001, little attention has been given to one conspicuous aspect--the event has no name.
We don't refer to the issuing of the Magna Carta as 6/15 (the date in 1215 when the document was published). The horrible event of November 22, 1963, is called "the JFK assassination," not 11/22. It's "the Challenger explosion," not 1/28, and "the Oklahoma City bombing," not 4/19. Nor were these events referred to or identified by their date of occurrence in the confusing early days and months after they happened.
Our reference to 9/11 is empty of substance. We aren't explicitly referring to anything about 9/11 except that it was September 11. So what's in a name—or, in this case, what's in no name?