It seems like this expansion is all about grinding experience. You need mastery abilities in order to even continue the story missions. I'm at the point where I need the mushroom jump things in order to continue the main story. Kinda disappointed because I don't have much time to play and it's a pain to gain mastery experience. I played for an hour yesterday killing things and doing events and only made it to about 45% mastery experience. Seems like this expansion is a massive grind, which I thought ANET was against..
On a side note, does doing world PVP stuff grant mastery experience?