It is irritating when you are used to a global auction house. They went with that approach as an anti-bot measure. End result is the design is annoying but it helps prevent botting, which can also be annoying. I've never been one to play the auction house game to make a profit but apparently those who do say when bots infest MMOs they drive down prices making it hard for legit players to make cash on the market. If true then the annoyance of the guild store is offset by not having to compete against bots trying to sell stuff.