Because nobody outside of the birther circus is buying it.
I mean, the fact that Obama's father was not a US citizen was a VERY well-known fact during the campaign. It got plenty of discussion here at FR. If that simple fact was, by itself, a Constitutional disqualification, you'd think somebody would've mentioned it long before the election.
But no, Birthers only discovered their favored 'two-citizen-parent' theory right at election time. And they've since spent the two years AFTER the election trying to convince themselves and others that that's the REAL definition.
Actually there is a large number of people who do. They are the ones who set up the coverup. They are counting on the ignorance of the average American to sustain it. This case is HUGE in-terms of the constitution. The letter in the P&E makes it very clear why. You should read it again.