Lots of interesting things can be done without root. The author gives an example where he quits and re-launches Chrome with flag "--disable-web-security" which

Lots of interesting things can be done without root. The author gives an example where he quits and re-launches Chrome with flag "--disable-web-security" which disables the same-origin policy. He launches Chrome to a webpage which then steals your Gmail session cookies. Most of the useful things you do on your computer, accessing all of your data, etc. doesn't require root.