The Itronix devices are just repackaged components made by the usual suspects in computer manufacturing. Panasonic has had a line of purpose-built ruggedized Windows laptops and tablets based on their consumer and office commercial products' components for many years. Motorola has provided repackaged components for military, law enforcement, firefighting, disaster response, forestry, mining, petroleum exploration and production, and other government and industrial sectors to complement their radio products that have dominated those markets for many decades. Dell has more recently done the same in order to compete on government contracts, and Lenovo has also done this in order to continue supplying former IBM government and industrial customers.
You're right, the enclosures from these ruggedized models might be usable to house a Pi board, but, integrating keyboards, trackpads, and particularly displays in them will be really difficult. Most such enclosures will require desoldering the connectors, and then there's the matter of how to access the SD card slot without disassembling the case every time you need to swap cards. The Atrix lapdock has USB and HDMI inputs, so, it's brain-dead simple once the right cables/adapters are acquired. Plus, the lapdock is feather light, especially compared to most ruggedized enclosures, and the new Li-ion batteries in the lapdock run circles around the old Ni-MH and ancient Ni-Cd batteries found in older laptops in terms of power longevity, recharge time required, etc., vs. weight. The $60 ~ $70 price for brand-new lapdocks is also hard to beat, although you're still stuck with figuring out where to put the Pi and how to route the cables. Too bad the Pi board couldn't' have been designed for the lapdock form factor, but, then, the designers had enough challenges with which to deal.
The best things in life aren't things ... but, a Pi comes pretty darned close!
"Education is not the filling of a pail, but the lighting of a fire." -- W.B. Yeats
In theory, theory & practice are the same - in practice, they aren't!!!