The second one : removing security.
The European regulations allow that for a while, but France was (as usual ?) a bit late for accepting this mutual recognition scheme (which means every Schengen country accepts that a passenger coming from another one has cleared security with the same standards).

And then airports have to adapt their infrastructure
- For Schengen -> Schengen, there is no reason anymore to segregate arriving and departing passengers (which makes flow management much easier).
- But for Schengen -> Non Schengen, it is necessary to segregate them so that long haul passengers connecting from a Schengen country don't lose the benefit of having cleared security departing airport. That's why ADP has to complete some works inside the 2F - 2E corridor before you can skip security by the end of the year.

Another good point, as explained at the AF DO, is that airside buses will then run under security clearance (as the 2G -> 2E one).