Military clothing is an important aspect of the military’s need for solidarity and cohesiveness. Much like any team or group, the members of the military need to implicitly understand that the man or woman to the left or right have their backs. This is true for any team, but for the military it is doubly so, since the level of trust placed in your teammates might include having your life in their hands. A soldier who attempts to do his own thing will likely run into trouble quickly. Movies tend to glamorize a lone-wolf or maverick soldier, but in real life, such things will likely get that soldier (and often others) killed. Military clothing helps to reinforce the idea that soldiers are not completely their own person, but members of a larger group. Military clothing is a constant, visual representation that the soldier’s identity is that of his peers: the military.
When civilians wear military styles, they too can partake in this sense of camaraderie. Wearing military clothing is a subtle way to be patriotic. Although the uniform itself is inappropriate even for military members in some cases, wearing odd parts of it can be quite fashionable.
There are several other reasons why military clothing is quite practical. One is that unlike many other styles, the military look is quite timeless. Servicemen wear what is issued, and the government is concerned less about style than function. So, things are not usually changed until there is a functional need. This means that those who wear military surplus jackets and other clothing will have something that is timeless, and virtually immune to fads. A military jacket from 50 years ago will not look enormously different from one made today, and those who wear them tend to look in style even when styles change.
The second reason to wear military style is functionality and durability. Military clothing is designed specifically to last even when abused, and is often abused in day to day life. Seams are often double or even triple stitched, buttonholes are reinforced. On battle dress wear, seats and knees are often doubled, and fabric is ripstop cotton. Fabric is often treated with a flame retardant material. This means that it is very fortunate that these clothes never really go out of style, since you won’t be discarding them due to excessive wear.
All in all, the buyers of military coats, pants and jackets are generally very satisfied and happy, and transcend style for decades.