Well, the general plan is to support more sub-commands (like “mon stop ”, “mon status”, …) - that’s why the “launch” is there. As for “mon” vs. “rosmon”, “mon” is simply shorter. Since the shorthand is only available once you source the ROS environment, I hope that there are no collisions with other tools.
If so, you can still fall back to “rosrun rosmon rosmon …”.