FW has channels. PW has servers (a couple for PvP and few more for PvE). 2 completely different things. Both games I mentioned have open pvp, open pk or w/e you call it, with some areas (instances and beginner <lvl 30 areas) where pvp is not allowed, and it makes sense. You wouldn't want to kill your party members in an instance or not allow low lvls to develop and understand the game.
I don't rly understand what you mean by pvp requested or pk or open pvp. I think you mean open pvp is open for all without having to do anything and pk you have to press a button to open it. In both those games you had to do smth to open the pvp, in kal you had to put on an assassin mask and in pw i think you had to make a click, but once that was done, you could attack anyone, not only those who had pk on. And yes there were penalties in both games, but it was fun. Here I barely see anyone with open pk because there's no gain. I bet if you got bp from killing others more will have pk on.
Anyway I just wanted to point out that there are games with open world pvp/pk which have had success. I didn't want to start a whole discussion abt it
and I mentioned those two because they have very good GvG and alliance war systems.
You are right, channels would work, but I doubt this game allows it. Instead the pk system is designed here so you can't attack ppl more than 5 levels above or below you, which is a very good thing as you can't be attacked by someone 4 times your lvl
The beginner area in PW may have been up to 30 free, but If I remember it had mobs up to 42, and pvp tended not to occur there. I didn't play PW long, because I felt its lack of parties, and shared drops, and heavily gimped exp when someone tried to KS you, was not attractive. So probably the only pvp I saw, was when uber 60's were requesting battles with other players.
But keep in mind, you just said the key words, "beginner area." And there was also a problem with servers only. When you start on a PVE server, you can't transfer to a PVP server later. Generally speaking, players don't like getting PK'd while questing or grinding. That is why they choose a PVE server. That doesn't mean they don't want later on pvp.
As far as Kal Online goes, I know about the mask, but didn't know that other players could not pvp. From the videos I watched it was pretty much a giant pvp brawl.
I would note though, that Kal online only had one non Korean server, between all other regions of the world. That raises the question of whether or not it was a successful game (it may have been successful to you, but in general, what it successful in gaining a long lasting player base that promoted growth - I doubt it did, because the third Korean server was closed, and the first two shrunk, probably indicating the International server also suffered).
PVP is when both parties play with the objective to fight. PK is when only one party has the objective to kill the other, leading to a contradiction of intents. PK is usually high levels killing grinders, whereas PvP is usually big battles (sometimes it can be party vs party).