My personal statement talks about a particular interest I have, so at the end of each statement, I tried to personalize my last paragraph to explain why I wanted to go to that particular school (because I only applied to schools that had programs/journals/clinics, etc. that I am currently interested in). I figured it just added more depth to the essay and showed how my current interests can lead to a future career choice.
If you're just cutting and pasting "This is why I want to go to so-and-so law school", though, I'd just cut it. It doesn't add anything to your statement.