Then somebody hacks into a thermostat, uses it to burn somebody's house down for luls. The couple whose house was burned down tries to sue, loses due to the contract that says their only recourse is a refund of the 50$ even though WTF, it makes all the news everywhere, and the device is forever known as "that device that burned some guy's house down and they gave him a whopping 50 bucks". They're now out 50 bucks in direct cost, and a jillion dollars in lost sales.
We sometimes forget the economics side of things, but companies *often* forget the social side of things (i.e. if you treat people like crap, they'll tell their friends, who will tell their friends, and eventually you'll be "that company that treats people like crap". Unless, of course, you're a monopoly, or if all your competition is equally terrible, in which case do what you like.)