This armor was probably 3D printed, so it won't look exactly like the stuff made from ANH. It also, much like TFA armor, was made with the ability to move in mind. It will allow the stormtroopers to actually look and move like soldiers (they used British Army soldiers as the stormtrooper extras). This is a good thing as we can see stormtroopers actually looking and moving how they should as opposed to the quasi hunched over and hurried walk they had to do in the original trilogy. Also, much like the military of today, armor would be constantly updated by the Imperial Military Industrial Complex, and then fielded in waves to different units. So you would have new armor to units some units, and older versions to other units. Nothing wrong with this and it makes sense. Getting wrapped around the edges because the helmet isn't "domed enought" or there are plastic belts instead of canvas is the dumbest thing I've ever heard. Rogue One will usher in a new love of TKs with new generations of fans. That is what we should be excited about, not that it all doesn't look like RS kits!
