There are exploits that can be achieved with this mechanic.
For instance putting a dozen T9 Heavies in storage with full cargo while waiting for a particular systems state to appear so you can use them to try and swing the system to your advantage.
There are disadvantages, currently you can sell ships remotely and even when you die to raise money to pay insurance if you are daring enough to fly without rebuy, what happens if you leave one or two things in these ships? Can't sell them because they are being used as cargo storage?
What about ship transfer? Does a ship with cargo on board be restricted and can't be transferred? If that was allowed it would give people the ability to do high level missions with zero risk, stack missions to endless levels using stored T9's and then using ship transfer to move all the ships with mission goods to the destination and swap backwards and forwards to complete missions. But of course restricting ships with cargo from being transferred would lead to complaints about not being able to transfer ships because they accidentally left just 1 ton of gold bait on board
It's not just a matter of making it happen, there are changes that would need to be made across the game for situations and exploits that probably haven't even been thought of, personally a better solution to me would be temporary storage large enough to hold the goods in your ship if the one you are swapping to doesn't have cargo racks installed to give you the opportunity to put some in. The goods in temporary storage would of course be sold at galactic average if you were to leave them behind at the station.
Like it or not the entire galaxy has been designed with no in ship station storage in mind and changing that would require some very large changes across the missions and mechanics of the game so it's probably not going to happen in a hurry.
None of this matters.
Carriers introduced several thousand tons of fully mobile storage. It's already in the game.
How could one exploit a single ship's worth of temporary storage more than carriers which allow thousands of tons?
Players asked for commodity storage for years to the responding chimes of everything you just said and up until carriers I'd have agreed with some of what you said because fdev made it clear storage wasn't a feature. Yet...
Here we are. You can throw out as many game play or technical nays as you like, none of them are demonstrably true any more.
Specifically, what's being asked for is the ability to switch between ships without being restricted by the cargo you have aboard at the time. Carriers allow this functionality and then some. I think it's fair to allow the simple qol change to enable limited (very limited, don't want to trigger the forum carrier owners!) storage of commodities at any station, including limpets, so switching between ships without selling goods (or worse, having to jettison them first at stations without a market) is possible.
Limited. Just like carriers are limited. Only more so. You cannot store rare goods and if you hit the global (just like 120 modules is global) 800t cap (let's just say 1000t) then that's it... No more storage for you. No transferring of your stored commodities. Unless you sell or destroy the stored goods (remote destruction is possible, remote selling is not - the function is there to allow one feature), you're stuck with that same small store and it'll never move unless you load it to your ship or destroy it.
The change would allow seamless switching of ships, even if the target ship needs to fit more cargo space first (which this would allow, just like carriers do), the option to change a ship temporarily to go do something emergent then return to continue carrying your cargo later (just like carriers let you do), the option to switch out modules to go do something emergent then return to continue carrying your cargo later (just like carriers let you do) and the ability to just store a limited supply of something precious that you just want to use later like modular terminals or a small haul of painite or stolen goods (just like carriers let you do now, only carriers let you store thousands of tons and move it about the galaxy too!)
Given carriers, the only logical reasons fdev can't do that now is lack of resource or priority. And that's fine.
Still, it's a potential improvement to the game with (given carriers) no demonstrable downside.
Unless you think carriers need to have commodity storage removed? Validate your position fully if it's truly your position. But you can no longer claim it as FDev's position because they changed that the day they decided carriers would allow mass commodity storage and mobility.