Why use 'href=“javascript:void(0);”' instead of something more user friendly?

I'm new to web-design and javascript, and I don't understand why it's common for web designers to use the void(0) syntax below:

 <a onclick="this.blur();return false;" href="javascript:void(0);" class="btn">

Since this actually shows itself in the lower left hand corner of the browser, why not come up with a way to make it more user friendly? Maybe it's because designers don't have the time to do this kind of UI tweaking.

What would you suggest as an alternative to the above syntax that would be more helpful to the end-user?