You need to remember the presented trailer is from 2012 early months, all the details are being perfected, ships models add and old ones remade. Moreover it's a free to play mod, not a full paid production so there are less possibilites....
It's not the whole point after all, it is likely that NW team doesn't want to release ships that can move, it is possible it doesn't fit their imagination about the game, and engine resources to be spend. It is their problem and decision but by saying it is impossible is simply unfair towards us, players and customers.
