Why does the navy use blousing straps?

Well, now that all naval personnel are required to wear the NWU/Navy Working Uniform; similar to the old BDU style. It is required to blouse the bottoms of the trouser legs so that it does not come below the 2nd eyelid of the boot. the easiest way to accomplish this is to use blousing straps of some sort.

Prior Navy Seabee and Army Soldier