Why stretch a Semi?

[Prop Shaft]

my curiousity on this has gotten the better of me and I need to know. What is the point of stretching a semi to ridiculous lengths? Is it just a show truck coolness factor thing? Or is there a practical use for it? I understand needing extra length to make room for more axles/bigger sleeper, etc. But I see so many trucks with miles of empty frame between the cab and rear axles. Just seems to me like nothing more then a handicap on maneuverability. Im not trying to ruffle any feathers here, id really just like to know what others opinions on this are.