I don't see why not. It's only fair to females who enjoy ArmA as well, and it fits with a modern (or in this case, near-future) military. The argument about not having women soldiers in Afghanistan is silly because ArmA 3 doesn't take place in Afghanistan, and even then considering the amount of settings that mods and expansions bring to the table, I don't see why there shouldn't be female soldiers even if the primary map was Afghanistan.