Actually, I prefer having it work in roslaunchers. There will always be nodes that do remapping, so the rosrun rule for anything but the simplest tests will break down at some point so roslaunch is a good habit.
On top of that....if we wanted it to point to
/cmd_vel_mux/input/teleop, we'd have to hard code an absolute path into the system which kind of breaks best practice - that is putting topic names in relative namespaces so they can be pushed down by some other user if they wish.
Is rosrun www xxx actually much harder than roslaunch yyy zzz?