Who's watching you?

Given that I don't tend to want to re-visit search results once I've found what I'm looking for, why does Google apparently need to be able to know what I searched for yesterday or last week or last year?

Will this somehow give me "better" search results in future? I don't think so.

Will this allow others to monitor what I've searched for? Well, yes it could.

Let's say I'm engaged in a discussion about terrorism in a chat forum, so I look up Bin Laden and Bomb Making and Glasgow and Propane and so on...

John Law demands Google hand over information on searches and maybe this time they make the subpoena stick (remember Google only refused to obey the previous one because "it might reveal proprietory algorithms" not because it was a breach of Civil Rights!) and "Oho! We've got a terrorists suspect here...!"