Does lag matter that much in that kind of game ? It's not a shooter game.
Depends on what and how you play... in GW1, playing a dedicated interrupter using arrows or spells in an attempt to interrupt enemy spells and actions that have, depending on the action, 0.5, 1 or 2 second cast times.... yes it can matter a whole lot if you try to react on a skill to skill / spell by spell basis.
On the other hand top of the line PvP gameplay often was about anticipating an opponents action more than reacting to it. ("oh he stopped running, guess he ll cast a spell next" or "oh look his teammate is going down fast, if he doesn t cast his big heal right now it's over." or "he always uses that skill right after he uses this skill... let's see if he does it again". et cetera)
Also keep in mind that you can dodge projectiles in real time simply by moving out of the way in GW1 and GW2 as well. In most MMOs that is not possible.
So the answer is kinda yes and no.
