Exactly, of course you should focus on your most profitable demographic when launching a new product. But once you have a sustainable business it's important to think about where your money will be coming from in the future.

I doubt anyone will say that tobacco companies marketing to teenagers is a bad idea because they can't even buy the product yet. It ensures the long term profitability of the company.

Well, you're implying there's a great deal of foresight and future investment going on :P

I don't think the turnover from Facebook is currently high enough for "management", as it were, to care about the opinions of a few teenagers.