Let's not use WW2 as an excuse(I take it you mean all-female Russian units etc), we are now talking about wars and conflicts in the 21st century where soldiers are mutilated and sometimes beheaded, which subsequently sees such acts broadcast worldwide via various media.
The goalposts have moved 180 degrees since WW2.
It's not conventional warfare anymore, it's largely about anti-terrorist and counter insurgency operations.
As an ex infantry soldier I can recall situations where for want of a better phrase some skull thumped others and physically manhandled their colleagues in order to get them to switch on and start performing at optimum.
Wouold that be tolerated? How many would feel that they weren't able to carry out such actions in extremis when warranted as a result of gender?
In Crossmaglen SF Base there was an area where the troops rested/slept. It was called 'The Subs' because it resembled a submarine, a small walkway with 8 bunks either side. It was roughly 24 feet long, 10 feet wide, 12 feet. I can't imagine the problems that 1 female alongside 15 males would have caused.
Moving on to the present day, we see young Servicemen minus limbs on an almost daily basis. How will the mood change if we start to see ever increasing numbers of females in the same situation? Move that on to the present. What will be the next conflict that we will become embroiled in? Doubtless it'll involve Islamic militants/terrorists. What will be the mindset if a female befalls the same fate as this poor lad?:
http://www.dailyrecord.co.uk/news/scottish-news/scots-soldier-highlander-scott-mclaren-1089061
Would we be able to stomach the torture and defiling of a female Servicewoman from the FEBA(Forward Edge Of Battle Area) being broadcast all over the internet by said insurgent group? In all probability they would target such an individual, were she spotted.
It's a dreadful sight when we see our Servicemen repatriated in Union Jack covered coffins, what will be the mood of the general public be when it's females in ever increasing numbers?