The bottom line is that well over 90% of PCs sold have Windows. That's a monopoly, and the only reason why IE is the world's number one browser. Think back to when the EU (EC?) brought these charges against Microsoft. Was the version of IE we had in the late 90s/early 00s ubiquitous because it was good, or because it was bundled with the OS on almost every computer? It was becoming apparent at the time that the internet was going to be important, and it was also apparent that IE was going to act like a braking force on development and growth of the internet. Microsoft at the time were so smug about their position that they actually stopped development of IE.
You could argue that Mozilla did more to change that than the jackbooted legions of Brussels, but eroding IE's dominance has been positive overall.