My guess (I'm not an engineer) is landing weight limits are more then because the airplane will never have more than that anyway. They need a little better suspension in case of a hard landing, and different training for the aircraft (which you need anyway) to account for it handling differently, but otherwise it is still an airplane. Maybe bigger spoilers or some other part as well to better bleed off speed.

They need to account for it of course, but it seems more like account for it, not difficult. Any engineer in this space able to comment?