And when the company decides that drinking is bad? Single and engaging in unwed sex? Hot rodding cars or other "dangerous" hobbies? And who decides what activities are hazardous and what aren't?

It's a slippery slope. It's no company's business what I do in my own home. If I break the law, that's one thing. But the last time I looked, smoking was still legal. When the Govt. outlaws smoking, then and only then can the business say No to it. Otherwise they can butt out of people's private lives, regardless of how it (and other _bad_ things) affect their insurance.