Like, if the game was "sandcastles simulator" and you play that, and do nothing but run around crushing sandcastles that other players spent weeks making, are you completely in the clear ethically because you can claim you were "just playing a character who's a bastard"? What if I stomp real, actual sandcastles, then claim I'm not responsible because I was only "play-acting" as a bastard who likes to stomp sandcastles? It's not really any different.
If a game is about building cool castles, I'd agree it's unethical to arbitrarily mess with new players' castles.
If a game is a medieval politics and warfare simulator, you don't get to receive special treatment. Understand that PvP in this game is not so much about actual destruction of characters or stealing their lands, but primarily about vassalage and building realms via negotiations or coercion. And it's not some novelty philosophy of the genre, things have been like that ever since OGame and the like. You just had to join clans to not get wrecked by old players and grow within those frameworks.
Seriously? Really? You just said people should be prepared for completely unmerciful beatdowns if they dare play an MMO, or just GTFO for being weak, now you want people to go softly-softly and "respect mah feelingz" when they trash-talk you for being a PK-er. Really?
It's not about feelings but about distorting facts.
Also, stop treating this game as some sort of WoW or Lineage. PK-er, really? What does that even mean in a browser strategy game?