As we know, game companies develop games to make money, thus they only consider how to make the most profit out of the least input as they should. In the case of GW2, it is unlikely for PVP balance to get the attention it needs if other aspects of this game (mainly PVE) promise better profit with less input required. Therefore to make it reasonable to spend resource on PVP balance, it needs to somehow yield a profit that's on par or better than the other aspects of this game.
Late edit: I think I fail to make the point of this thread clear, for which I apologize. Here I'll clarify that by saying "better balance" I mean the assumption of literally better balance, the ideal situation where our payment will guarantee a better balance in all terms than it is now.