So, I've been on the server since day one.
I've only ever played Vanilla, retail or private.
Now, I may be wrong, but it seems to me there is one factor in particular which shapes the character and nature of PvP in WoW - and that is that it is impossible or nearly impossible to find someone of the opposing facton (Horde/Alliance).
As such, when someone kills you - that's it. *You can't get revenge*. They're gone, and you can't find them.
This impossibility, or near impossibility, of future interaction inherently removes from players any consequences to their actions. No one they harm is ever going to be able to act upon what was done to them.
I see two in-game consequences from this.
Firstly, sociopathic behaviour lacks consequence and so is more commonly expressed; high level players enter into low-level contested zones and sit around killing all the low-level greys around them, etc.
Secondly, there is a significantly tendacy for people who have been killed, where they cannot get revenge, to end up mis-directing their frustrated anger upon *all* players of the opposing faction. This of course perpetuates a cycle of violence.