Mostly because you can get the benefit of improvements to the build config just by updating the one `react-scripts` dependency. For example, 0.8 enabled proper sourcemaps support in Webpack (and 0.8.2 bumped the Webpack dependency to fix a problem with not being able to set breakpoints in sourcemapped code). If you eject, you don't get those easy updates, as the config files are now a permanent part of your own project.