The African colonies benefited. The nations doing best afterwards are the ones who were colonized the most.

France has been paying immigrants. They have been a net burden on the country. See Was it worth it?

The people living in France now are not the ones who did what you think is bad. Family of the French who have been beaten and raped have more of a right to revenge since it is more recent. You would never end the cycle of revenge if you say that vengeance on descendants is valid.

There are many reasons Eastern Europe is poorer. Communism is one.