Graphical user interfaces are increasingly becoming the preferred type of user interface for many users.
Graphical interfaces are generally helpful to new and casual users.
However, a command language still provides some important advantages. Specifically, It provides portability to a large number of platforms. If a platform provides a reasonably good Fortran 77 compiler and sufficient memory, it should be possible to install Dataplot on that platform with a minimal amount of source code changes. Command languages are useful for automating routine or commonly performed tasks. Once you become familiar with a command language, it is typically faster to use than a mouse based interface.