Some of the stuff here contain optional/alternate versions, plus, a lot of them have only the pngs, not tids, so making one zip file and just copy pasting would lead to some priority issues (tid or png) if you already have other mods in (for instance, I have an HD mod in mine). And every time this gets updated, another one would have to be made, which is very inconvenient.
If you don't actually know how to mod this, just read the steam thread on modding this for instructions, it's pretty easy one you get it, though a bit time consuming.