Actually, in previous version of windows, Microsoft tried to make people believe that in windows 8.1, the version of IE is light weight and it is user friendly too. But due to old impression of IE, user don't believe on it.
So, they decided to remove the IE and launch a new browser code named Spartan. Though, it is not the final name and they have to launch the official name for next coming browser. This may be revolutionary in this field. This can change their image in the market of browser.