Repair is one of the most important skills a wastelander can have and it makes scavenging much more profitable; not a lot of people in post-apocalyptia want to buy broken items.
Equipment in good condition can also mean the difference between life and death when you're traveling the wastes. Your equipment jams less and does more damage the better condition it's in.
Fallout 3[]
Repair in Fallout 3 is just as important as it is in Fallout and Fallout 2. You need to keep your weapon in good condition or its damage is going to be next to nothing. If your armor is in poor condition, then it's DR is going to be negligible. Besides leveling, you can raise this stat by finding the Bobblehead for Repair; it's located in Arefu. Enter Evan King's house and when you do, turn to the left. This Bobblehead can be unobtainable if you fail a force lock attempt on the Average locked door.
Fallout: New Vegas[]
Just like every other Fallout game, the Repair skill is vital to a wastelander's survival. It better allows the Courier to repair and maintain weapons and armor, and later on gives you some great perks, like Hand Loader, which unlocks all ammunition recipes at Reloading Benches, or Jury Rigging: this allows the Courier to repair a weapon with a different weapon, ex. a hunting rifle with a varmint rifle. While there aren't bobble heads in New Vegas, up to five skill books can be found throughout the Mojave Wasteland, giving up to 25 skill points if a specific perk is taken.