Berlin does not need more density in the first place. They need more jobs. Work. Companies. Berlin already hasn't enough jobs and a relatively low GDP per capita rate - for Germany.
Jobs come with people. The more people, the more interesting the cultural life, the more exchange of ideas.
Berlin is still recovering from being surrounded by / part of a communist society. It will slowly normalise. Berlin is now the capital of a European power and money as well as jobs follow power.
