Many consumers want a flat floor inside the RV, with the slideout room floor being flat, same level as the main floor. In other words, no "fenderwell" for the tires to come "up" inside the coach.
That means the floor of the trailer has to be at least 27" to 29" off the ground. Makes the main frame of the trailer rather high. In order to get a reasonable coupler height for the ball, they manufacture these under frame components ( A-frame sections ) and possibly too, an underslung coupler.
As long as it's all welded together correctly, it works just fine.
That's my view of it anyway. My Funfinder is made this way, and one of the advantages of all this is very good ground clearance for uneven ground or roads that could have clearance issues. It's one of the reasons I chose this camper, because occasionally I go off the beaten path.
