We stare at our editor for most of our work day and sometimes even after that. So it is really important that the theme of the editor is not only visually pleasing but also provides good readability. There are a very large number of code highlighting themes available for the JetBrains IDE's, but so far I have not been able to find many themes that consider the entire IDE and all its components. Material Theme UI for Jetbrains by Chris Magnussen is so far the only one that I have found aside from the built-in light and dark themes.
Also applies to: WebStorm