I think it should be the default setting. Even make it not configurable. Why would anyone want to see just Readme or just Files view when it's possible to have them both?

This is something that has been on our minds for a while, and we must do it better. We created an issue for a smart project dashboard that aims to provide a better solution, it would be great to have your input there: https://gitlab.com/gitlab-org/gitlab-ce/issues/27112