It's faster, and it's more efficient. If you middle click in Firefox you open up a new tab. I know you probably rolled your eyes at that, but it does save time, especially when sifting though multiple threads you want to go to or say a google search? You're also missing out on a LOT in Firefox, whether you realize it or not. Microsoft won't comply with
W3C's standards. This may mean nothing to people with no web design experience, but for those of us who do have experience in web design, we know this means that IE is a broken browser.
The keyboard shortcuts save time, the fact that it's faster saves time, the fact that it actually SHOWS you the web page as the webmaster intended you to see it as saves YOU time.