This is the rub on units like these. As an example, lets say I make an aluminum or 3D printable enclosure for this PSU and I sell the complete unit to you. Now lets say because my enclosure design is poor, the power supply proceeds to overheat and burn your house down. The liability on this is massive and anyone who would bring a PSU like this to market under such a scenario would have to be a fool. The obvious workaround to this scenario would be to have the enclosure properly engineered and the entire unit re-certified inside the enclosure I'd designed before selling it. Once certified safe, my liability would be vastly lower were an issue to occur provided I could prove the complete unit was certified to operate within specification.
The problem with the certification process for AC-DC units in particular is that it is tremendously expensive. Speaking from experience, certifying the Dynamo 360 cost me about 1200 USD. The price of doing this for an AC-DC unit is many multiples higher because of the nature of the conversion taking place (I've heard figures into the tens of thousands are typical). Obviously this means that without a large market for this kind of supply, you're not going to see a product like this come to market due to the fact that amortizing thousands of dollars in certification costs over a relatively small number of power supplies is a massive financial risk.
I think you're unfortunately mistaken as to how the power rating system for power supplies like these work. If you look at the brick above, it is not rated for 200W when cooling via convection like the HDPlex 160W or 300W are. If you dig a bit deeper into the specification you can see that the supply downrates itself based on the ambient temperature. At 25C the output drops to 170W and continues to do so until it reaches an ambient temperature of 55C at which point it downrates to a mere 100W. The only way to have this unit operate consistently at 200W in a real world scenario would be to provide active cooling to the units.
Based on my research, other units of comparable size and wattage seem to require between 10 and 15 CFM of airflow to operate at maximum rated capacity (the spec sheet on this unit is pretty confusing as to exactly what fan specification would be required to run it at 200W continuously). While 10-15 CFM might not seem like a lot, you're not going to get this kind of airflow at an acceptable noise level under 60mm x 25mm. As an example, Noctua's 40mm x 20mm fan which you might think would be suitable for this application moves a grand total of 5.5 CFM.
https://noctua.at/en/products/fan/nf-a4x20-pwm
To put it into perspective, with passive cooling the HDPlex 300W AC-DC would likely move closer to 400W of power while the HDPlex 160W AC-DC would likely move closer to 250W. At this time the only really viable work around to these heat issues is to move to a higher efficiency power conversion process like that provided by GaN (Gallium Nitride) based solutions. As of right now, this technology is too expensive to be practically applicable to our community. About a year and a half ago I priced out a 250W unit in roughly this form factor from Transphorm USA and they wanted about 550 USD for it
Personally I think the best bet going forward is to engineer a supply on a load-sharing based platform, but thinner. As an example I'd put forth the Bel Power 180W unit here:
https://www.digikey.ca/en/product-h...solutions/180-w-abc-mbc-series-power-supplies
My thought is that by making the unit a hair wider and longer you could likely use cheaper parallelized components to drive the cost down significantly (think 4.50" x 2.25" x 0.75"). The benefit of the lower height would be that there would be ample room to add a very capable heat sinking mechanism without making the unit too large.
