I guess there are a few reasons for keeping the hair
short...
1) Image. So as not to look like a motley crew of guerilla army.
Which professional army in the world allow their soldiers to keep
long hair?
2) Hygiene. Imagine how dirty your hair will get if you are out in
the field for extended periods. Heck, even one day, one night
outfield will make your hair as clean as a broom!
To me personally, I have no problem with keeping short hair cos
that has been my style for the longest time. It's neat and tidy.
And you can easily style it to look good. Look at all the hollywood
stars, none of the guys keep long hair, or not many. While I do not
berate your choice of hair style, I personally find having long
hair for guys a little sissy. Especially for those who are not
suitable for it. But well, that's just me.