laptops that you can't sit on your lap

Why do they call laptops - "laptops"? I have been having some trouble with my laptop lately. It's been getting hot and the fan is getting LOUD, and I was reading on the manufacturer's website that they recommend that you don't place it on your lap, as your pants do not promote ventilation. Which begs the question - what good is a laptop if it cannot be placed on your lap? Oh, and before you offer the bit of advice that, "there are colling trays that you can buy to sit your laptop on your lap", ask yourself why they didn't just include this into the laptop design in the first place. What a joke. I guess they should have just called them skinny desktops.