Since Commodities are required for higher level crafting, and since they must be held in the cargo hold, it seems that all crafters who wish to further their chosen profession must also be Day Traders.
I read an earlier post from Dec. 2015 on this but did not see anything else.
So, if the game requires all crafters to also be day traders, it would be useful for players to be informed of this up front so they could research trader skills and crafting skills at the same time. Otherwise, they reach a crafting point where they are “dead in the water” and unable to craft new items until the trading skill level catches up.
I understand from the previous post why commodities work the way they do, but it would be very helpful to inform players that if they choose crafting, they should be sure to begin their trading career as well. Maybe this requirement could be mentioned within the text of an early crafting mission.