It is a shortcut...it didn't exist before the Dark Below. What you had to do was buy vendor gear, but it topped out at 29. This basically allowed you to start running Vault of Glass. 30 gear only dropped in VoG. People spent a lot of time trying for that 30 gear (of course back then it was the pinnacle). Ask Skribbles, apparently he could not get any to drop for ages.
With Dark Below the vendor gear went up to 31. Which kind of allows people like you to skip a lot of the previous grind, you do not have to grind VoG for 30 gear.
As I said, it's fully what Bungie intended. A shortcut so new/lapsed players dont feel intimidated by the grind.
You can read Xalion complaining about it up there. He's saying the next expansion, the vendor gear will be 33 if the past is any indication. So lets say you, nightshade, do a fair amount of grinding eventually and reach 32. With House of Wolves, a new player will have 33 gear available to buy as soon as he can. That might bug you a bit. Especially if that player was to come in here complaining about the grind...