3/4 Ton vs 1 Ton

My problem with the 3/4 ton diesel is; why offer it? What advantage does it have over a 1 ton SRW? Ford use to offer a 1 ton srw with a 10k gvwr option. They maybe still do. The option was available at no additional charge and consisted of a different door sticker than the 11500 gvwr 1 ton. I understand there are certain states that charge more for licensing trucks with GVWR over 10k so this option makes sense but why would anyone want a diesel pick up with the overload spring removed?