Mainstream fashion has been influenced by military dress trends for literally centuries. The clothes you wear today wouldn't be the same if it hadn't.
Clothes fit better and are more comfortable because of the military's influence.
And, really, the world isn't perfect, we aren't at a point where we can just stop having a military and be Flowers and Bunnies Okay. If there weren't those Stupid People in the Military, kids wouldn't get to be Stupid People Not in the Military and you'd have even fewer freedoms to play around with.
I'm not in the military - I'm not even patriotic, I'm just realistic. As cliché as it is - freedom actually isn't free, and while many things suck, they could still suck more.