They're not necessary at all. They're available, but really you shouldn't care about them unless you're very paranoid. These settings are basically the equivale

They're not necessary at all. They're available, but really you shouldn't care about them unless you're very paranoid. These settings are basically the equivalent of telling your computer "I don't ever want to search the internet unless I manually navigate to google.com (or whatever) and do the search there". Because that's what you're doing, you're disabling the internet-enabled search functionality.