Jace, what you seem to not understand is, this isn't just like the "Furry" fandom, it's like ANY fandom.
I've seen gore pics for Sailor Moon, Card Captor Sakura, Pretty Cure, Dora the Explorer, Hell I've seen Songebob gore.
These things are NOT mutially exclusive to Pony's or Furry, It's FANDOMS as a whole. I've seen Picard/Q Ship fics before I knew what shipping was [it also does not help that John De lance and Patrick Stewart were PLAYING them off as gay, don't believe me look up interviews of the two.]
I remember people pairing Sailor Senshi together in their spare time. Why, because THAT'S WHAT FANS DO! It's just part of the whole experience.
It's like saying who will win, the Alien or the Predator [a question that was being asked WAY before the AVP movies came out]. It's all the same kind of thing, just on different levels, if you don't like it, just avoid it, But don't expect the rest of the fandom to STOP just because you don't like a certern aspect of the fandom.
Despite your dislike for R34, I guarentee you there are some VERY beautiful fan works out there within the 'r34' moniker. i've seen absolutely beautiful artwork that can be considered such I know... I've also seen absolutely beautiful normal works. I've seen horrendous work on all fronts also it's all part of it.
But instead of focusing on the positive, people tend to focus on the negative. EWW there's pony pronz, eww there's pony gore, eww there's fanfics like Cupcakes, EWW There's Sexual themes in FoE... Why do people get so squicky about sex? Sex is a biological thing, every animal on the planet does it, and if you wanted to go so far as saying the pony's are just animals, then they're not going to care. If you want to akin them more to humans, than they're going to do that kind of thing behind closed doors like we do. You can't have it both ways.
Fallout Equestria. Yes there are sexual themes, some of these even walk the line into rape terrority [which is certernly a thematic element in FoE:Project Horizions.] but it's just part of the overall story. and in Fallout Equestria, the first major sexual scene is considered an offshoot fanfic that's just filling the gaps between 2 chapters. You don't HAVE to read that, you're not forced to, it's optional, and was written by another author, not Kkat.
But you have to stop and think, what are the psychological issues these characters deal with in regards to all the horrible things they are experiencing in the wasteland? That is why there's so much of that kind of stuff in FOE and in other fanfics, It's the psychological aspect.
Might I also add that, ponydom isn't exactly the nicest of places, There's mythological creatures out to kill ponies, there's cocktrices turning pony's to stone, Dragons that are known to steal and eat ponies. And ponies themselves have shown rampant Raceism, distrust, encouraging a holoday that ostricises one of their princesses, overall disharmony and bullying.