It's actually been quite a while since I used Internet Explorer, and while things have improved (or so I've heard) at this point I'm still sticking with Chrome. That is not the case with other users though as IE usage is up lately. Of course that could be due to the fact that Windows XP slid this last month and Windows 8.1 is up. My guess is that people can't figure out how to install Chrome and are stuck in the Metro interface using the App version of Internet Explorer.
If you wondered why these companies want you to use their browser rather than a rival's, it is because there is a lot of money on the line for these products even though they are free. How do they make money? Well, it all comes down to searches. For Firefox, Google pays them hundreds of millions of dollars to be the default search engine and on Chrome, Google gets the default search preference too, while on Internet Explorer, Bing gets the nod as the default engine.