Google’s web history tracks your searches history and allows you to view it at any time in the future. It gives you a choice to delete certain searches, it also gives your mom, the police, and hackers an ability to explore this diary. Whether they use it for blackmail or prosecution, its not good for YOU.
So what gives with it being enabled by default on all new Google accounts (even non-gmail accounts)? This should really be something you opt-in to.