Well kept facial hair requires more discipline than simply shaving every day. Facial hair also has a long American military tradition, as can be seen on the faces of several distinguished officers prior to WWI. Additionally, a lack of facial hair may make the wrong impression on our enemies and allies.
As we have seen with the Sihks, a gas mask seal can be made. So this cannot be used as a reason. As for professionalism, that is subjective, many studies show well kept facial hair is seen as more powerful. Discipline was addressed above.
There is no good reason to be bare faced. Please sign this petition to allow WELL KEPT facial hair in our military.