Early 240Z floor jute - stepped pattern?

I have some photos I downloaded a few years ago when this project started, of the front floor jute. These, for example, have file names like "Kats repro 1970z", etc. I might have downloaded from here! Anyway, I'm trying to figure out 2 things:

1) would the jute in my 1970 Z have had this "stepped" cutout pattern, or not?

2) anybody know why Nissan might have put that pattern in? It's not like there are floor plugs there. 

Here's examples without it: (photo, for what it's worth, is labeled "jute-1970 240z":