I've not seen the video yet, but there are other ways of balancing huge haulers than simply changing their capacity. Planet sized cities like ArcCorp will be a huge sink of consumeables that will be needed at scale unless that city generates produce and caters to its own needs.The ability to even load or unload a big container box freighter like an Hull C/D/E will be severely restricted to port-side equipment which may only be available at the largest of ports, such as the System to System hubs I expect there to be in every major population center and be moving large scale consumables like food, water, toilet rolls, cloathes, components, medical supplies, fuels etc that can be moved at such a scale as to make it pointless to put 4 SCU of it in your 350R unless there is a drastic need for it somewhere and it is requested specifically. The Planet/Moon Trade Center to System Hub can be taken care of by large landable freighters like Cats etc, and the production facilities to Planet/Moon Trade Center can be for Connies/Freelancers.
I don't expect the Kracken standard version to have the equiptment to be able to unload that cargo quickly by itself and it will need port facilities to move any amount of gear quickly. The Kracken Priv I not only expect to have less cargo in favour of a marketplace, I also expect it to have internal auto-load systems to fill customers cargo holds very quickly and empty suppliers holds just as quickly without port facilities. The Standard version you'll be pulling all that stolen swag out of your cutlasses fairly quickly as there won't be much dribbling in to your cavernous hold, but you won't be stopping a Hull and just filling up your hold super quick as if by magic. No port loading facilities, you are doing it the long way... Or sacrifice some of that cargo space to install an auto-load...? Lets say... 50%?
You ever notice how Semali Pirates hold huge freighters and their crews hostage but don't seem to be in to keeping the ship and unloading the gear for their own personal gain? Those pirates don't have the facilities to get that freight off the boat and if a Hull D washed up on the shores of some fringe system I very much doubt they'd be able to unload without a few days or even weeks of Argos shuttling the containers off the craft, if they even have Argos on the Fringe at all. Manually moving SCU's off a Hull could take months.
I think the craft with a sizeable hold that can land, like the Kracken and the BMM will be the maximum, but even then I don't think the non-marketplace versions of them will be very practical without port facilities. I don't expect the BMM to loose it's capacity even with an Auto-loader, but I don't think you'd be able to look at the thing and not think "Loot Pinata" either. Potentially a BMM could be used as the end-game trading game, where you land on a major planet and compete with the whole planets commerce system. Cue some planets banning BMM's and they'd have to saty in orbit and compete from there.
I also expect the main cargo that would demand a ship with a 3500scu+ hold to be low value consumeables like food that only make a decent haulge value at such quantities and would not be worth being targeted by pirates. unless they were starving pirates, then throw them 20sku and they'll eat for a year.
Balanced!