Nothing in AO is strictly PvM or PvP.
If there are only new playfields no matter how interesting they might be for you, I might not find them worth enough to buy the booster. Mind I am saying *might*.
But if those new playfields come with new loot tables that can make significant difference in my toon development, I might find it worth. Its not just about items, its how those items affect my gameplay. If they could be significant enough (in my opinion) to change my enjoyment in whatever aspect of the game I like, then I can decide the booster pack is actually worth buying.
But to decide on that I would need much more info than I have right now.