Meanwhile, Tribals in various Fallouts run around with spears/etc. People use the weapons available to them. And that they can maintain & find/make ammo for. There's no lore reason why there wouldn't be bows/swords/etc.
And this argument again. You do know that bows - modern ones - are reasonably easy to find at any sporting goods store, right? And that "swords" (medieval replica, military, machetes & similar woods tools) are also still manufactured?
Just because people got tired of hearing "it's Oblivion with Guns!" about Fallout 3, is no reason to knee-jerk object to any "fantasy" weapon being in the Fallout universe. Again, remember the Tribals (and Caesar's Legion. And the Chinese Officer's Sword. And axes. Etc, etc, etc.)
All that said, there are practical game design reasons why they haven't bothered with things like bows - fitting the weapons into the skill & perk categories. A bow isn't a Small Gun, isn't an Energy Weapon, isn't a Big Gun, isn't a Thrown weapon, etc. And it'd be silly to either jam bows into a category that they really don't belong in, or make an entire skill (or perks) just for a single weapon (or even a handful, if you had Longbow, Compound Bow, and another variant). As well as more animations that aren't like any of the others. Etc.
So, yeah. I wouldn't expect to see bows. But not because of any silly "keep your Olde Tyme weapons out of my Fallout! " reasons.