Make the (Black) Color Swatch a TRUE BLACK
In the Appearance Panel, the (Black) color swatch is not a TRUE BLACK color and when this color swatch is used and a file is exported to PDF, Rich black is not achieved.
The attached document shows a few shapes that are black. The top right is a true black color and the color swatch had to be changed from the standard (BLACK) color swatch in order to be achieved when exporting to a PDF. The left and bottom color swatches have the (Black) color swatch from the appearance panel applied.
Please, Please, Please, make the (Black) color swatch a true rich black color (since users cannot adjust this color).
Since the standard (Black) color swatch isn't true black, it will take me quite a bit of time to apply a new color to all my previously designed files that use your standard (Black) color swatch.