"What kind of a retard brings a ranged weapon into a dark, dank, can't-see-more-than-10-feet cave?"
One who can obviously run faster then his enemies and pelt them with ammo? One who doesn't want to get into melee combat with his enemies? I am pretty sure that Legolas didn't drop his bow and arrows the second he went into the abandoned Dwarven home. (I think he was with them).
Though mind you that your not in a cramp cave... each square represents over 5 feet making certain rooms in the game larger then my house.
I mean it is hardly stupid to bring bows and arrows into the dungeons (Afterall, it would be like saying Strike wands are stupid since all they are is a strong ranged weapon)
Where does it say each square is 5 feet? If that's true then the main character is 5 feet tall and 5 feet wide, and hedgehogs are 5 feet long.
And have you ever shot a bow, crossbow, or a gun? You can't aim for shit unless you're standing still. Hell, you can't even string an arrow on a decent bow while moving unless you're a professional. Wands work because there is no load time and they're highly maneuverable...you just aim it and something in front of you asplodes.
And if you want to bring LotR in to this, think about this point: Legolas is certainly an exception because he is an elf and trained in how to use a bow unlike anyone else in the LotR universe. But guess what? In all the other siege scenes in the books and movies the archers are up on a wall firing from hundreds of feet away.