The main thing is that it's just inconsistent.
In ship engineering all materials can be traded. And in suit engineering one of three types can be traded but all three types can be sold for credits implying they are transferrable and there is some kind of market for them. (and some have no other purpose but you'd have to guess which ones unless you're really into making spreadsheets.)
It's just so clearly an arbitrary choice to drag out the acquisition of the actually usable ones.
In ship engineering all materials can be traded. And in suit engineering one of three types can be traded but all three types can be sold for credits implying they are transferrable and there is some kind of market for them. (and some have no other purpose but you'd have to guess which ones unless you're really into making spreadsheets.)
It's just so clearly an arbitrary choice to drag out the acquisition of the actually usable ones.