I have read and seen comments about light Jerkins that drop but can't be crafted among other motif issues that many seem to disagree about even being issues... it seems to me that the answer would be a Common or No Motif line, no item is used to set the motif, the items made are plain, unadorned... totally commonplace.
Gear level is set the same as it is now and basically everyone would know the motif (or lack thereof) and traits could be applied as they currently are, improved as currently crafted items are... the only thing that may have to change is perhaps tinting based on the material...
Basically, everything that is currently done with a crafted item could be done to the common item, except no motif item will ever be returned when deconstructed because there was none included in the creation.
Of all the things I have lost, I miss my mind the most...