Something new.? PVP?

The biggest problem with a direct PVP system is the delay players have between each other due to the path client-server-client.

This. I still don't know why they haven't worked this out yet. It's noticeable if you want to "race" someone in Maplestory. I always find it funny when people in party quests argue over who got on a specific box first.
"I came here first!"
"No, are you blind? I was here. You jumped on it as soon as I got to it."
"Nuh uh, get the fak off noob! I have pro level 193 Night Lord, I KS you if you don't get off!"
"BUT I GOT HERE FIRST~!"

Shut up. You both got there first. But the MS delay is stupid, and while your screen showed your opponent lagging behind you by a few seconds, their screen showed the opposite.

Or if you're a class that uses ice skills to freeze a fast monster. When someone else comes onto the map, the monsters won't freeze where you want them to. They'll slide around like ice cubes on ice, in order to adjust to the spot the OTHER PERSON is supposed to be seeing them at.

So if direct PVP is implemented, how the hell can melee classes even hit anything if their screen doesn't accurately show them where their opponent is? On their screen, the Night Lord is in range of their sword, but on the Night Lord's screen, the Warrior is still walking up to him. What the hell happens now? The Night Lord Flash jumps away, but at the same time the Warrior hits attack. On the Warrior's screen, he hit the Night Lord. On the Night Lord's screen, he escaped the Warrior's sword without getting hit.

Lag sucks.