In Mark's Amazing Ending, Jesse Johnson identifies the purpose of Mark's actual ending:
The book also ends with a powerful evangelistic thrust. So far, the only person to open his mouth and positively identify Jesus as the Son of God has been a Roman—the same soldier responsible for his arrest, trial, and execution. The apostles haven’t said it, and neither have the women. When the book ends with the phrase “And they said nothing to anyone…” it serves as a rhetorical device: will you open your mouth? Will you join the centurion and even the demons that identify Jesus as God’s son? Will you tell others? Or will you go missing like Peter, or silent like the women?Read Jesse's entire post.
When the ending of Mark is seen as it was written, it ranks with Judges, Jonah, and Revelation in terms of having a powerful ending that raises a question. Do you do what is right in your own eyes? Do you have compassion on the lost? Do you long for the Lord’s return? And finally, are you amazed at what Jesus has done? You should be, and you should open your mouth about it.
I concur entirely with his observation: "knowing that those final 11 verses of Mark 16 are not Markan should actually bolster one’s confidence in the transmission of Scripture, not lesson it."
I argued the same in A Tradition of Translation Timidity:
Leaving passages like Mark 16:9-20 and John 7:53-8:11 in the same flow of the canonical text - just because the publisher does not want to handle the deluge of angry e-mails that are sure to follow their exclusion - just seems irresponsible.Identifying what we know only serves to hinder the Church's confidence in Scripture's transmission. Ignorance can bolster neither confidence nor conviction.
Furthermore, this practice actually undermines our confidence in the inerrant text and undoes all that was accomplished in the Reformation's call to sola scriptura. For a vigorous application of "ecclesiastical usage" amounts essentially to a Roman Catholic view of binding authoritative tradition.
By not distinguishing these inauthentic passages - something like Wallace's footnote proposal - we are truly doing a great disservice. By offering a more transparent admittance of what we have known (for centuries!), we give greater witness to the text of Scripture and greater credibility to the preaching and teaching within the Church.
Mark actually ends with "... for they were afraid" (16:8) and that is the best ending (or question) that the Spirit of the Lord could have ever superintended for His Church.
After all, it is the beginning of wisdom.