By 1954, Christiansen's son, Godtfred, had become the junior managing director of the Lego Group. It was his conversation with an overseas buyer that led to the idea of a toy system. Godtfred saw the immense potential in Lego bricks to become a system for creative play, but the bricks still had some problems from a technical standpoint: their locking ability was limited and they were not versatile. In 1958, the modern brick design was developed; it took five years to find the right material for it, ABS (acrylonitrile butadiene styrene) polymer. The modern Lego brick design was patented on 28 January 1958.
Even in terms of play value it mostly seems to be a trade-off — 60104 loses the vending machine, cafe, baggage x-ray scanner, and a few seats on the plane but gains a baggage conveyor, a restroom, a refueling tank for the plane, an additional minifigure, and more seats in the waiting area. It's pretty nice to see the value of a LEGO air terminal remain fairly stable even though the price has not increased.
Other than the planes, I do find it unfortunate that the Friends set focuses on shopping and food like so many Friends sets, and I also think it is unfortunate that the City terminal only has the basics of the airport structure in the control tower and service truck. Having a control tower for the Friends set would have been great. Having a gift shop/cafe for the City terminal would have been a worthwhile addition and not something we have seen in many City sets.
Parking capacity at Copenhagen Airport was greatly expanded in 2015 with the construction of a new lot as one of the first phases in an ambitious airport expansion plan scheduled to roll out in the coming decades. There are several lots: those near the terminals are very expensive, while the further-flung ones are cheaper (but have free shuttle bus service to the terminals).
City has had many games since it was released. One in particular, The Robot Chronicles, was a cross-over game which saw the City, Racers, and Agents 2.0 all together in Lego City, where the player controlled and unlocked vehicles in each theme to play through a campaign. This campaign/game was also tied into a My LEGO Network The Robot Chronicles campaign- playing the game earned rewards in MLN which could be used in that campaign to eventually get the Key to LEGO City.
The remainder of the build is the control tower and terminal building. First there is a metal detector screener leading to the waiting/secure area of the airport, which seems taller than it needs to be for the minifigures. I think the same effect could have been made with half the height, except that would not allow for an impressive height for the overall tower. However it does seem to be similar to many modern airports with the high ceilings. This area also seems to be someplace to check luggage as evidenced by the rather nifty conveyor belt that comes in a full part. The moving parts of the set include a revolving door (a very tall one, for the first floor) that leads from the secure area of the airport out to the tarmac, and of course the conveyor belt.