Vintage clothing works well with modern styles for several reasons. One is that it avoids looking like the wearer is overly concerned about fads or fashion, but still looks put together and decent. Fashion trends cycle in and out, and generally a look that goes out of fashion and then comes back stays in for longer than something that is only in its first generation of popularity.
Classic fashions are similar to classic music. That is many people have the idea that music created more than a couple decades before present day was better, in general, than music made within the last 15 to 30 years. They cite things like auto-tune as being a killer of talent and genuine creativity. These critics of modern music seem to assume that all music made in the “good old days” was, on average, much better than that made now. However, music, fashion and other forms of artistic expression tend to go through a filtering process. As artists produce music, initially even the poor quality, but catchy tunes might gain a following, especially among younger listeners who have less developed musical tastes. However, as time passes, fads fade, and only the truly good quality music retains any sort of popularity.
In the same way, clothing fads that are simply fads will fade off the public radar after a while. Extreme looks, much like extreme music, simply don’t last as well as more moderate ones.
Vintage clothing doesn’t just survive fads, it also survives the test of time physically. Vintage clothing, and military vintage clothing in particular is made to last. Many newer articles of clothing are made to last for only one or two seasons, which makes sense because the fad that they belong to will not last that long either. There is no sense in making an jacket able to last for many years if the owner only wants to wear it for one winter. Vintage clothing tends to have a more conservative look, which means that it needs to last for many seasons.
Finally, vintage clothing is often cheaper than designer clothing. Since it has been in the public eye for so long, the supply is usually high, which drives demand and pricing down. Also, many vintage clothes are available only from second hand or consignment stores, which drives down price still further. This lower pricing means that the buyer has extra leeway when it comes to finding proper sizes, since alterations can be figured into the price of the garment.