Although no Airbus document gives the reason it is true that they have submitted for certification that all abnormal landings will be in CONF3.
Not quite true, the QRH/ECAM gives the actual flap lever position for landing.
For instance single HYD failure can be in either, single engine can also be in either. Lots of abnormals that can be done in Config Full, and lets be honest, any brake system failure that affects stopping distance should probably be done Config Full.