The trunks can be done for fan service while having a practical purpose in the film as a harness utility for holding his belt in place. I threw together a quick manip. While this is not a professional result, it illustrates the point. To me the new 52 trunkless costumes just look like long pijamas that need something to break the monotone color. Even the MOS trunkless design that so many are praising didn't work for me.
In the end, there is so much talk about an element which will be covered in shadows most of the time and we will only get a glimpse of it.
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