Bows and crossbows are perfect weapons for a post apocalypse. Ammo is easy to manufacture, weapon maintenance is a breeze, and both are extremely lethal in trained hands. There's professional hunters in real life that prefer a modern crossbow over a rifle for hunting, as they're lighter, studier, and easier to maintain. Also dammed near completely silent. With a proper pulley setup and a scope, a crossbow turns into a terrifying medium-range sniper weapon. Stealth players will adore it.
No no no. Your forgetting in FO3 there was a dart gun in the form of a cross bow. It crippled all limbs, what is not to love!