Why does the A330 sit nose-down on the ground?
For one reason or another, the main gear was made longer that originally planned and it was decided to avoid the cost and weight also extending the nose gear to match. The nose down angle while rolling along the ground is no big deal one way or the other, except for looking bad and disconcerting passengers who wonder why the plane is tilted forward. 

Lots of airplanes are like that, sometimes because of changes made during development, but more typically after fuselage stretches where the main gear had to be made longer to keep the extended tail off the ground during rotation (the flying pencil CRJ1000, which I used to be type rated on, feels like a backwards taildragger in that regard).  Obviously, the freighter needs a level cabin floor for loading, hence the nose gear band-aid; for the passenger versions, it's not really necessary and the blister and extra structure to do all that is just ballast and drag, serving no useful purpose.