There are only TWO reasons that I can think of to have stacks:
1: Your 'rig' is an 18 wheeler (duh)
2: To bring the exhaust up to clear very deep water crossings (and this is stretching it)
Although, reason 2 is rarely applicable due to the fact that most do not waterproof the engine.
wow your an idiot i will agree that those stack are pretty bad however stacks were used for keeping the exhaust high enough so that it didnt go straight into the stock trailer they were hauling thats why you see real cowboys with really tall stacks the other are just for show some look good i think you can have your opinion others i think we all agree look like 
I'm not quite sure how this makes me an idiot. I have never hauled a livestock trailer and I have never seen anyone around here hauling livestock trailers with stacks. I am, however, man enough to realize that you make a good point and I can see where someone would think that stacks would be good for stock trailers. So, make that reason #3 on my list of reasons why
I think someone would want to run stacks.
Also, before you question someone's intelligence, how about learning to use a little punctuation and capitalization. I had to read your post 3 times before I figured out what you were saying.
