@tuatara1
Probably since... the first thing that would probably came out on most people's head when they pair a "downed female" and and an asshole like that, were mostly that, especially when the other subject is "a beautiful girl" since I think much of it came out from delusion and the author's likes and dislike more, rather than based on research on what the many possible outcome that can be done in this kind of situation. (with some limitation, since it's a published material... you wouldn't want someone to report you when you are going overboard with things after all)
There are other of course... more brutal thing that could've been done first instead of straight out raping to make things more interesting to some, like for example, making sure the subject wouldn't be able to move first, like chopping things up, or maybe feeding the subject to monsters rather than raping them, etc-etc.
Well I wouldn't really bet much on variation from a syosetu titles. especially in this kind of title.. where fantasy setting were used.. or rather than the fantasy... the game/trpg system.
And... from the many title that I read, not many really dare to do more than an "attempt" rape anyway. or something that give much long lasting mental scar... (that or I probably misses things like that)
Heck, not many even implement "sex" in their story even when the plot were going that way...
Much like those that avoid killing any main cast for good, even when it can progress the story in an interesting way.
And when there are those someone that include those kind of depressing material in rightful manner, peoples would complain anyway, so not much really can be done... still, I'd still like for some variation at least.