Police, EMS, fire service, and military use them. The laptops are often mounted inside of the vehicles and need to withstand a fair amount of bumping around. A lot of them also specifically include RS232 ports to interface with industrial equipment as well.

I daily used a semi rugged for a while for shits and giggles. Actually wasn't bad to lug around, it had an inbuilt handle made it easy. And there was very little guilt about quickly slamming the lid shut so moving it around from place to place was actually easier then you'd think.

These ruggedized laptops (I have a Dell variant) are the only way to get a sunlight readable display. It's true they're heavy.

Sometimes you need a self-defense device and laptop all in one.

When you knock a mugger down with one of those, he stays down.

Yeah - I've used toughbooks in the past, and honestly they're 6x more likely to survive being dropped, but also 3x more likely to get dropped in the first place because they're so heavy.