I think the fact that some of the best players in almost every trade, town, and combat group have spent $0.00 or $2.00 on the store shows that making store purchases is certainly not a pre-req to achieving great success in this game. In fact, you can actually earn store credit IN GAME. Meaning, EVERYTHING from the store can be obtained from in-game efforts, and even everything from the current perks of being a customer can be looted and obtained. Since NOTHING is 100% locked to store purchases and can be obtained in game I do think complaints are a bit of a stretch.
Do you advance faster if you throw money at the game.
Yes
Do you advance farther and faster to which a player who doesn't cannot compete?
Not at all