Ash Lake is really the perfect example of this. I mean, it's hidden behind two illusory walls for Christ's sake. Unless someone's using internet references or their friends have spoiled it for them, who would have actually found it by themselves?
Yet, Fromsoft made the game area anyway, knowing that a lot of people would never even access the content.
 It's a pretty ballsy design choice. Another reason I like Fromsoft, they're not afraid to take those risks.