Excellent post.
And I remember Watergate very well. The truth came out slowly, over many months, and those digging into the scandal were soundly ridiculed.
Also, during Watergate the conspirators set traps for those attempting to uncover the truth. As depicted in the movie, "All the President's Men", one of the conspirators was asked by Woodward or Bernstein whether a certain report was true. The conspirator answered, "I would have no problem with that", falsely indicating that an assertion was true which was, in fact, false. This got Woodward and Bernstein into trouble and could have caused their investigation to be abandoned.
Perhaps we are seeing the same thing here. The Kenyan BC appears to be a forgery. Who benefits from having a forgery which is debunked in several days? It is of no lasting benefit to the "birthers". But any premature claims about its meaning undermines the credibility of those who are seeking the truth.
So, who has the motivation to undermine the credibility of the "birthers"? Obama and his followers.
Whoever forged the Kenyan BC did so with the expectation that it would be accepted as valid. I think there may be a crime committed here. But since the media didn't seem to care who forged Dan Rather's memos, they probably won't be interested in this.