Why not make all the airstrips that are on an airport available for landing as well as take off? Because often there is a que at one airstrip while the other is not in use.
And maybe even the option to build extra airstrips and expand the airports even further. Some airports are just too small to handle all the aircraft.
p.s. : When is Schiphol becoming available? 
No, and no
Okay, a man with an opinion…Can you elaborate?
Inactive runways are at PRG and SYD and they’re inactive because they intersect with other active ones (there’s even a recent FAQ post explaining why PRG’s second runway won’t be used).
Which RWY will be used for landing and/or take-off depends on the assigned stand.
There was talk of adding the possibility to choose departure RWY in one of the Q’n’As (and I think it was even mentioned in one of the Dev Blogs), but as always with no specific regarding when would it be added.
Airports are operated similar to how they are in real life including runway operations.
Expanding the airports further with extra runways will never be in the game as it is strictly based in reality so unless a new runway is built in real life a runway won’t be added.
Schiphol will most likely come in the future but there is no guaranteed dates
There is already a publication that explains it well.