I couldn't say. I constantly see people crying for restrictions on higher level players attacking lower levels out of supposed malice. Personally, i don't think we need any restrictions past possibly restricting repetitive harassment of weak players while they are in their own kingdom just doing PVE.
Yes, but the issues we have been having recently is low level players going into our kingdom and acting as spies. Never attacking any cities but scouting targets for high level players to hit. They get left alone because they are lower level but having that free range can be dangerous.
Honestly i would like to see a system much like the surrender system. Something that would let any player no matter their level PvE in the game without the ability to raid cities/castles. Something that would also be a visible flag on the player in the world. It would also have to be something you could not toggle off and on to get protection while also raiding in between. So once you toggle it on you are in say PvE mode for the rest of the day(twelve to 24hrs). You can go around and get mines and PvE, but cannot raid or even look at cities while in the mode.
Or hell even better have PvE on a separate map. Make it more like the tactics school. Where anyone can do the PvE and not have access to the real map. Thus stopping people from using that as an excuse. Then again I do not know how feasible or realistic that is.