If you're a solo player, and you skip 3-2 and go right to 3-3 you cannot do the mission once you have accepted the later one and are stuck on it. Now at this point you have no way to get past the door without help. You cannot do the mission, you cannot do level cap quests (that need higher rank) because you can't get past the gate without begging someone to open it for you. This is against many of the changes they made to the game, so this appears to be an oversight.

As I said, a simple fix is just to make 3-2 required instead of allowing people to skip it.