this is exactly why Muslims will never hold a high place in government in the west
First of all, please try to see things in context. If you never noticed, it was the pagans themselves who broke their side of the treaty with the muslims (which was peace from both sides - the muslims and polytheists), so because the polytheists broke their side of the treaty, what were the muslims supposed to do? Stick to it and get harmed even more? Makkah fell into the hands of the muslims. And even then, there was rarely any bloodshed at all.
At that time in history, the people who were 'taken over' would become slaves to the rulers, whereas God's Messenger, Muhammad (peace be upon him) forgave them all for the severe torture which these people had given the muslims previously - when they never had a state. And all of them were given equal rights, whether they were the lowest class in society, or if they were the nobles. Whereas before this, the low class of society would remain oppressed, and the oppressors would remain in power.
Also, the world belongs to God/Allaah, and He will give it to those who are Just. This is why the believers were strong and had authority in the land when they were just, when they stopped their justice, Allaah removed it from their grasp and gave it to others for a temporary while.
Take this into notice also - the fact that those who don't like the justice of Islaam are willing to overthrow Islamic governments, so they shouldn't find it shocking if the opposite was to occur. And my previous post will also clarify many things also.
And Allaah knows best.
Regards.