How can the 12v Train 7823 Container Depot be used to load container ships as per Lego Catalogue
Whilst there is quite a bit of clearance on the crane as it stands, the Container Ship (4030) was quite a high sided beast - although you can see that better on the catalogue page:



I would think that a bit of extra height from the hinge would be useful to make it over the edges of the ship - assuming you haven't raised the crane's base.

The alternative answer is that they are trying to make the model more real-world accurate, where the cranes lift up as the ship comes in, and then go back to flat to load: