Language has power, and using "men" in this context makes invisible the contributions and bravery of these women and others like them. Sorry to seem PC, but it's important to get this stuff right if we want our kids to grow up in a better world.
That's ridiculous. When people use men in this context, they refer to humanity as a whole. Don't confuse your lack of English understanding as being PC.
So "women" is a collective noun for a group of humans all of whom are female, and "men" is a collective noun for a group of humans who are some mixture of males and females. There's no collective noun for a group of humans all of whom are male? Doesn't that strike you as a bit asymmetric?
I understand that "men" is sometimes used in the way you describe, but I believe that people who do so consider male the default gender of humans.
Brevity is the soul of wit. You certainly lose accuracy, but honestly, nobody wants to read a wall of text.
If you want to presume some sort of conspiracy sexist default supremacist undertone in what I wrote, fine, but I think that says more about you than about me.