One of the reasons those wanting storage have quoted is that they can't transfer cargo when they buy a new ship. Well I proved (to myself at least) that it is possible and here is how it happened.
On one of my missions I saw the station was selling rares. I haven't got involved in rares so like an inquisitive child, I bought the lot, all 44 of them. Got back to my home station, and found that I was actually going to make a loss on them. Bit of research showed me I needed to travel at least 300ly to get a decent profit. That is when my mind went sideways and my impulse gland kicked in. Decided I needed a long range, high volume ship with decent weapons and survivability stats. That little discussion in my head resulted in the purchase of an Anaconda. Yet my Corvette had 44T of these rares on board, how could I possibly do that without having a storage facility. To make matters worse, I actually complicated the issue by deciding to trade in my T-9 after stripping it. This wasn't a real impulse thing, I did spend a good hour going through various builds on Coriolis and working out what modules I had in storage, and what modules I could steal/retain from the T-9 (ended up not having to buy more than a couple of modules for the Conda!).
Anyway, swapped to the T-9, the goods swapped across. And because I had done my homework, I knew without a shadow of doubt that a brand new Anaconda come with 6E, 5E, 4E and 1E cargo racks, that is 114T of cargo space and I only needed 44T. Home and hosed, not an issue and all done without worrying about storage.
Now to shoot down the complainer: If I was buying a ship that didn't have enough cargo space I would have waited until I got rid of the rares or just sold them for a loss - I was spending millions, the loss of a couple of hundred credits is so insignificant it doesn't warrant thinking about.
So, it seems the impossible is possible, go figure lol