Adding my suggestion to the pvp toggle idea:
Have pvp be strictly opt-in only, similar to War Mode in World of Warcraft. Players can only enable/disable their pvp flag inside towns. As per robr's suggestion, this could work by using easysigns inside towns to toggle pvp on and off, potentially having individual towns modreq for the signs OR by using a toggle command that only works inside town regions. By using this implementation we could enable pvp outside of arenas for people who wish to partake, while also preserving the pve experience for those who don't. Additionally this has the added benefit of not only giving pvp some teeth, but also curbing combat-logging or afking to avoid combat AND incentivizing exploring other towns all at the same time. I believe this is a happy middle ground that allows players to tailor their own experiences on P without stepping on anyone's toes.