Kuwait340,
Sadly, I know nothing of Airbus types, so I could be talking out of my hat! Please excuse me therefore if what I say next is total tosh.
Could it be that V2 is based on 1.2 x Vs whereas approach speeds are based on 1.3 x Vs? Thus raising the speed in the take-off case ensures a greater margin to provide sufficient control response/effectiveness, which is a given in the landing case as a result of the greater margin above Vs.
BSD.