I'm not sure I understand anything new by looking at this. Cool graphics, but is there some key point i'm missing?
Also it is quite interesting to see the different programming languages used in projects. For example, Git has almost as much Bash scripts as C code: http://tomiaijo.github.io/github-treemaps/#/repository/36502... .
That may be nitpicking, but I think it also goes to show that sometimes seemingly simple numbers or visualizations can miss subtle but important points.