See Elite is not about 15 stored Cutters with 700+ cargo capacity each stored with a large amount of cargo total of 10,500. Which would cause game lag which is not needed for us. It could also ruin it for other players game. When they find a exanomic boom for one item. It could be fun for 40 or so people in mid or large ships. Just to be ruin by one player that has 15 stored cutters with the same item. It would make it so unfair. It would make that Boom into a bust.
Elite is about ONE SHIP ONE PILOT and what you do with that ship is how you make your funds. Not a fleet of ship use for storage hold on stuff until you find the next economic boom.
First thing, it's not one ship one pilot game. Most of us have several ships, each of them used for specific purposes. Which means that having cargo, whatever type of it, locks you in a ship and activity. Frankly, it's not a huge problem, because in most cases you can just sell your commodities from your trading vessel, jump to your combat vessel and off you go. So in this case, storage would be "just" a quality of life issue, where you can quickly switch between the ships and perhaps thanks to that enjoy more dynamic gameplay. It would simply be nice not to be locked in a ship. OP rightly mentioned that there is a workaround players use. So your fears of somebody being able to affect the ingame economy can already be true, to an extent.
The simplest solution of this issue and answer to this suggestion would be having 1000T of storage galaxy-wide, in a way similar to modules storage. Although I would not allow for transferring it between the stations. Such a solution not only allows you to quickly switch between the activities and ships, but also prevent carrying around 16T of modular terminals and such, attracting unwanted attention, not being able to do much else until you get 25 and get your invitation to Qwent (which is buggy, by the way, so you might end up waiting for it ad mortem defecatam). I'm sorry, but I fail to see how implementing something like this would have any detrimental effect on the game universe. For sure it's a logical solution to have in a game where players can buy and sell goods and also change means of transportation of these goods. It would open some additional possibilities, such as hauling large quantities of goods to a big station and then ferrying it of in a smaller, combat capable ship to an outpost in a dangerous neighbouring system. This solution doesn't harm the players, doesn't harm Frontier and doesn't harm the BGS in any way, but it sends one important message from Frontier: "hey guys, we like players to have options and be able to decide what they do ingame and when".
I don't believe we are going to see something like this implemented, but I would very much like to be proven wrong and see Frontier issuing such a message.