I'm not fan of long hair, never had long hairs but I do like my short Iranian style beard, up to 2cm long, gray in the middle.
Beard longer than 2cm is too much for me, it's easier to maintain and doesn't itch.
I don't want to derail the thread too much. So, I'll simply say that I spent many years where short hair was required, and facial hair was not allowed. Well, you could have facial hair if you somehow got a doctor to sign off on it being a medical necessity. Even then, it had to be pretty tight.
When you were in the field, you could be excused for not shaving -- but that's also when you'd want to shave (much of the time). Your gas mask doesn't work properly if you have facial hair. Plus, depending on your MOS, you were required to present yourself in a standard (and imposing) manner.
For example... Embassy duty was tough in many ways. You had to be squared away at all times, and your uniform needs to be exactly correct. You're not supposed to show any emotions, and the time you spend getting everything right is not considered a part of your duty time. Your hair needed to be uniform at all times. and any faults were spotted and corrected. Repeated problems meant more duty time and/or restrictions.
Then, you are expected to present yourself in a professional way when you're not on embasy grounds. Though you do have some diplomatic immunity, that's only during the course of your duties. Even when you're off-duty and outside the grounds, you're expected to wear appropriate clothing and act accordingly.\
Ah well...
If need be, we can split this off to another thread.