What do terms do for you? They define your relationship with visitors. The default position of the law gives these people a lot of rights. These rights can be invalidated however. The way to do this is with your terms. Let's look at an example.
Copying From Other Sites
The first reason is you are infringing on someone's copyright when you copy terms from their site. How do you think the lawyer who wrote those terms is going to react when he or she finds out what you've done? You might as well dress in raw meat and go poke grizzly bears to get a feel for how they are going to react. You are inviting a legal disaster of epic proportions.