In May 2007, Google launched a plug-in that made browsers more powerful by integrating advanced features like offline storage, local database, location services. Google Gears added invisible features that allowed web applications to become more responsive and to work even offline.
The trouble with Google Toolbar and Gears was that users had to install them separately, the browser integration wasn't very smooth and there were many other things that could improve web browsing, but can't be added using a plug-in. A better JavaScript engine, a more reliable browser that crashed less, a fast and simple interface - it's hard to make all these things happen without building a new browser. If Google Toolbar made it easier to search using Google, Chrome encourages to use the web more because the browser loads instantly, you can find web pages faster and you spend less time waiting for pages to load.
A press release from 2000 explained that "Google exists to provide the world's best Internet search experience. Google accomplishes this for millions of users daily by delivering a powerful, fast, and easy way to find the most relevant information available." Google changed the scope of the mission from improving the way you search the web to improving the way you experience the web. A better browser, along with a faster Internet connection, great web applications and an open environment that encourages innovation bring more Internet users and, as a consequence, more Google users.