Imagine what this (ability to store goods in ships and then park them somewhere) would do to, say, Powerplay or CGs. Have your PP faction slowly build up a huge quantity of PP goods at some station of interest and then deliver them suddenly just by switching from ship to ship unloading cargo. No warning or chance to respond by the other PP factions at all. You could also get seriously rich if you parked ships filled with Palladium near player CG that you knew was coming up and paid well for said material. There is pain in not being able to store goods, but the opposite would be game breaking.You have a 700t cargo ship full of goods.
You then jump to your other cargo ship and fill that with goods.
You jump to another cargo ship.. and another.. and another.
I never said you said anything about hording commodities; but that's exactly what it would be used for; I was explaining (one possible reason) why we don't have it.