I love my little 5 x 8 utility trailer because I can unhitch it and push it around a tight campsite without having to use my truck. I make use of this convenience just about every trip. The down side to an open trailer is the dust! Everything gets covered with dust!
I have started making a tree to clamp into my 5x8 to conveniently hold our kayaks, paddle boards and bicycles. This will leave the bottom of the trailer open for firewood and supplies in Rubbermaid bins.
Those enclosed trailers look really nice BUT the ability to move my little trailer by had is really nice!