@AC1 and AC2
"It sounds like it's got an ordinary hard disk. Wouldn't a SSD be more rugged?"
That might be the case, but a lot of this kit is designed to work with datalogging equipment etc. which probably works better with older H/W (hence the serial ports)
"for that sort of money you could buy three or four standard ones, and replace your lappy every year when it gets trashed."
Picture the scene, your in your tent in the arctic wastes, and your cheap laptop gives up the ghost. Who's going to courier you a replacement?
Another possible reason for using the case as a heatsink might be to keep the batteries warm and prolong battery life.