If you take the time to learn ggplot2 you are going to learn a lot more than plotting. Depending on your purpose for learning ggplot2, that could be great or perhaps frustrating.
In my experience learning R has opened up many other content areas for me. Granted there are many paths to learning new things but I am not sure how I get to my list below if I stayed with a learning path emphasizing spreadsheets.
- Linux
- Git
- Web-development
- CSSS
- HTML