“That [the idea of going up to the front gate] would be no good,” said the wizard, “not without a mighty Warrior, even a Hero, I tried to find one; but warriors are busy fighting one another in distant lands, and in this neighborhood heroes are scarce, or simply not to be found.”
But, of course, Gandalf did happen to find a “burglar.” And he would do quite well for what the Dwarves needed. Of course, they would need a lot more, and Bilbo would happen to fit that bill as well. So however scarce heroes happened to be “in this neighborhood,” it seemed Gandalf found one of those as well. Though Bilbo’s role in dealing with what came out of the front gate would not be quite what was envisioned at this initial meeting. Nevertheless his heroics at the front gate proved to be quite important to the conclusion of this tale.