I guess it have something to do with model polygons and weapons
For example every model have XXX polygons to look nice but also there is game engine barrier of how many polygons your model can have to balance big battles for mid PC, if DF and Exel will be same size like in movies then Exel will just crush that polygon barrier, huge model with same texture tedail as little Delta.
And weapons, i think curret structure of them is like, every ship have hard point from where beam\cannon shoots but all beams and canons of same type use one model and texture, so if delta would be little ship then beam you fire will be just same diameter as ship, akward looking thing. If exel will be bigger then we go to my first point of polygon barrier. Solution to this could be just different models for weapons.
i can be wrong on both my points
