It's important to deter Microsoft's actions by others, by setting an example. Microsoft must understand its place and play by the rules of the market it hopes to profit from. And it's important for the people of Europe that their representatives are backing them up and enforcing the laws meant to protect them.
Microsoft didn't break any anti-trust laws in the European Union, yet the entity chose to punish the company with a huge fine. Unfortunately, such behavior is unjust and the technology giant didn't deserve such a punishment. The company can still appeal the decision and should do so to get it overturned.