Allow custom sort order on date types

I was surprised to find I could not have a cross table with just a date value as the row value, and could not have the most recent date at the top of the cross table.  I thought I would just go and adjust the sort order on the column and create a custom sort order (or descending sort order) and wasn't able to do it.  I had to fudge things by adding a rank of the date values and add it as a value to the pivot table, sort by this field and then hide the column to get the most recent dates at the top.  I believe it would be very useful to specific the default sort order of all data types...custom, ascending or descending.