The game has to remain fair for everyone.
The EU said Microsoft failed to live up to a commitment it made in 2009 to give European consumers a choice in what browser they wanted to use. Microsoft eventually developed a “browser choice screen” so people could choose between using Internet Explorer, Google Chrome, Mozilla Firefox, Apple Safari, or Opera. But a “technical error” on Microsoft’s part prevented that screen from being part of Windows 7′s Service Pack 1 and therefore users were still defaulted to Internet Explorer.
And here is EU’s original letter.