How do you propose that one types an email? Enters a web address? Go it iPhone style?!

And why would you need a touchscreen to browse the web? The only things you would do on a website are enter the address, scroll, type into forms, and click a link. A touchscreen only addresses the very last of these, while a keyboard deals with all of them. A button on the side of the screen - or a vertical touchpad even - would easily solve the button problem.