I feel that balancing weapons under the assumption that “if you use a certain type of weapon, you’ll stick to that type exclusively” is a bad idea.
There’s nothing stopping you from using multiple weapons other than purposefully making a character with very min-maxed stats.
Archery and melee serve different niches.
Archery is safer, but requires time to prep arrows.
Melee is riskier, but requires no ammo.
Melee wouldn’t be moot. It would just be another option. You sacrifice some safety for some extra convenience.
As for builds, sacrificing 14 points just to use a powerful weapon with easily obtainable ammo from the get-go isn’t that balance-breaking when you can spend 8 points and start with a monomolecular blade without taking any negative traits.
The 14 points doesn’t even include the skills you need to be able to craft it from the start, you’ll need spend even more points for that.
18 strength will still allow you to slaughter zombies with melee early-game fairly easily, as well. This isn’t really a greatbow-specific issue.