Well, that's all true, because people sacrifice other things as well in getting a fully-rugged machine: screen resolution, weight, $$$.
My biggest need for computational horsepower over the last few years has been to run virtual machines*. It would have been nice back when I needed a hazardous-location-rated machine if I could have only carried one computer to both host a VM or three and to take outside in a plant. But hazloc-rated means fully-rugged, which means I took a hit on max RAM, CPU, screen resolution, and weight (weight I didn't much care about). My use case may be unusual, but I'd still like to be able to carry just one machine on trips.
It looks as though there may be improvement on this front however, with Haswell chips making heat somewhat less of an issue, and tablets making high-res screens popular again. Max RAM seems to be going up as well (speaking of which, you DO need a 64-bit OS to fully utilize even 4GB of RAM). I'm holding out hope things continue to improve, because I too like the build quality of rugged machines in general and Panasonic in particular.
* VMs can make web browsing faster (I don't have the patience to make something look pretty in Word), because they're a great way to keep your base OS install clean and free of cruft and intentionally-induced breakage, er, testing