There is definitely a market for magic boxes that just need solar, battery connections, and fuses/breakers. The big advantage is that there is a single configuration to deal with, possibly easier management as well.
The down side is that a single component failure can take out the entire system. Of course with LFP batteries that is also the case with a BMS failure (assuming one battery). Though with my DIY pack I can bypass the BMS for emergency operation.
Another downside is that you need to design around a larger box, instead of a few discrete components. Pay close attention to the manual for orientation and ventilation requirements, and leave room for wire routing.
A plus side is that there will be fewer fires, as folks won't be temped to mount all their components to a big wood board, and a lot more of the connections are pre-done, and inside a fire rated enclosure.
There aren't many van applications for this stuff that are mission/life critical. Victron got their start (and a fair bit of their business still is) from the marine sector, where a system like this would need to be doubled up in deep water applications for redundancy. As opposed to a system with separate components, where you can operate without a solar controller, inverter, etc for emergency usage if needed.
The dimensions aren't bad, but like many Victron products, the configurations options are a bit sparse. Such as no higher output 12V option. 1600VA doesn't have enough overhead to run an induction cooktop or other full power 15A device, which is a problem IMHO. At 2,000W/VA is the transition point where higher voltages should at least be considered. I would have done a 24V system were it not for the 1.2kw of charging I can get directly from our alternator, with no additional gear required. Above 3,000W/VA 24V or 48V is essentially required anyways.
All-in-one style boxes have been offered for big setups for a while. They typically have had normal off the shelf discrete components inside, and the main bus wiring, breakers, and interconnects are all pre-done or at least provisioned inside. This reduces installation time, makes it easier to meet code inspections where applicable, and makes the system a bit easier to organize.
A major issue for higher input/output systems is heat generation. At some point putting all that gear in a box requires major ventilation, which can be loud.
As mentioned my main issue with Victron gear thus far, is that many of their products are not terribly cohesive, and configuration can be a chore. Though their somewhat regular firmware updates are a very welcome feature.
In the end the DIY market is a very small slice of the pie for them, and they are targeted at professionals building systems for hire, often in the marine market, but increasingly in the land based mobile fields (almost always the mid-high end).