Actually, these days, war movies of all kinds show a lot bloodier and horrific deaths deaths than just falling down. Have for some time now. And the sheer number argument is quite valid, whether you think so or not. It's not just crowd size deaths, it's the sheer number of deaths depicted throughout the movie or Manga/comic.
It's not just that either. It's the sheer number of works of all kinds which depict deaths of males far more than females. Take your, example, slasher movies. The vast majority of slasher movies depict more male than female deaths, often twice as many. There is a site that gives deaths by gender. Here are a few well known examples:
Saw .................................... female:0 / male:6
FRIDAY THE 13TH PART 3.................. female:5 / male:7
FRIDAY THE 13TH (2009)...................female:4 / male:9
FRIDAY THE 13TH PART V.................. female:7 / male:15
FRIDAY THE 13TH PART VI................. female:6 / male:11
THE TEXAS CHAIN SAW MASSACRE............ female:1 / male:4
THE TEXAS CHAINSAW MASSACRE 2........... female:0 / male:6
THE HILLS HAVE EYES PART 2.............. female:3 / male:5
I KNOW WHAT YOU DID LAST SUMMER......... female:2 / male:4
I STILL KNOW WHAT YOU DID LAST SUMMER... female:2 / male:7
URBAN LEGEND............................ female:3 / male:5
SCREAM.................................. female:2 / male:5
WRONG TURN.............................. female:3 / male:7
WRONG TURN 2............................ female:5 / male:8
CHILD'S PLAY............................ female:1 / male:3
HALLOWEEN 4............................. female:3 / male:13
HALLOWEEN 5............................. female:3 / male:13
SILENT NIGHT, DEADLY NIGHT.............. female:4 / male:10
SILENT NIGHT, DEADLY NIGHT PART 2....... female:6 / male:20
DEATH VALLEY............................ female:2 / male:5
MY BLOODY VALENTINE..................... female:5 / male:7
MY BLOODY VALENTINE 3D.................. female:10/ male:19
SWEET 16................................ female:1 / male:5
SLEEPAWAY CAMP.......................... female:2 / male:9
SHREDDER................................ female:4 / male:8
HELL NIGHT.............................. female:2 / male:6
HAPPY BIRTHDAY TO ME.................... female:3 / male:6
Some of them have ratios of 4 to 1, let alone 2 to 1.
Such lesser known gems as ...
EVIL LAUGH.............................. female:2 / male:8
HUNTER'S BLOOD.......................... female:0 / male:10
RETURN OF THE FAMILY MAN................ female:5 / male:23
The list goes on and on.
Feel free to check it yourself. hysteria-lives.co.uk
Of the rest, most have a greater number of male victims, or, at the least, an equal number. This thing about slasher movies being all about the killing of females is absurd. And most are not erotic, just bloody. What is this "erotic" thing? Kind of narrow, isn't it? Of course there is the odd movie in which there are more female deaths. Sometimes only female deaths, but they are rare by comparison. D-Day (Korean movie) is a good example of a large number of females deaths. Some things even rarer, such as the slaughter of several females at once. On the other hand, a female slaughtering several males at once is quite common. Oh, and the heroine rarely dies in the slasher movies. Usually she is the only survivor.
Again, my original point was that, overall, there are so many fewer female than male deaths depicted that sites like this spring up to cater to the desire to see the female deaths. Or to at least concentrate the images of such in one place.