PvP is much bigger in those games. look at XI's PvP. PLD and RDM were clear kings. RDM was damn near unstopable, and PLD/RDM was almost as bad. I remember we did an LS event and i was taking people on 4v1 as pld/rdm. it took a SC+burst just to break my stoneskin. and the only reason they could SC at all was because of /sam.
it depends on how big a role PvP will play. most of the formulations are based on dlvl. IE: tanks will excel. the DD classes are wearing paper armor for the most part so they will pale in the face of tanks, seeing as the tanks primary mode of keeping hate is damage. . .
IE: the best way to balance PvP and not nerf PvE is to add a PvE element to PvP. beat up the other players, but to win the objective you have to do somethign with the environment also. which is why i made specific suggestions to do so.
And while PvE 'suffered' i can't say a lot of the nerfed skills were beyond usable after. i didn't play any of those games long, but i did a lot of PvP in SWTOR as a tank-assassin. I raped a lot of face. when operative was nerfed, people wined and cried. but when it came down to it, they weren't hurt that bad in PvE. it just wasn't easy-mode anymore. just like the archer nerf, people will always wine and cry when something gets nerfed. but if it's broken in PvP it's also probably broken in PvE. it's just less noticeable.
again, PvP is most likely to be broken by the tank classes, since they are currently a combination of survivibilty and damage. something the DD/Caster classes lack. adding a global buff for the PvP instance can fix things. Taking from dominion on League of Legends, a global nerf to defense would help. tanks will be near damage cap because of the low defense on DD/caster classes anyway. so it would really just balance out damage done to tanks.
