It's required for some perks and for many recipes that use the work and reloading benches.

Correct me if I am wrong, but doesn't it also reduce the damage items you have suffer?

Using the Major at Mojave Checkpoint - to repair the Gobi Campaign Scout Rifle cost over 3000 caps from its initial condition found in the Sniper's shack - and that is just one weapon. Sure caps are plentiful, but 3000 caps is still a lot of caps to be spending on one weapon.

That's almost one implant right there.

And those unique weapons that can't be repaired with any other regular weapon, yep, good luck with that.

Repair Benefits:

Craftables - More things to make at Workbenches and Reloading Benches (With the Hand Loader Perk you get more ammo recipes.)

Quests - Several quests can be completed and areas accessed via use of repair.

Jury Rig - Cuts repair costs waaaay down by letting you use common, cheap items to repair rare and expensive ones.

and here's the big one...

Item Durability and Effectiveness - While you can repair all items to max durability w/o repair, a high repair skill makes items last longer before losing effectiveness. You can see this in the inventory menu by looking for the black brackets on the durability bar. These brackets indicate where your weapon and/or armor starts to lose effectiveness (Lower protection, Lower Damage/Accuracy/etc.) There is in fact no need to repair items beyond those brackets. As long as your durability bar is higher than where those brackets are your weapon and armor functions as if it was fully repaired. Repair Skill lowers those brackets for all weapons and armor. So having a high repair skill means otherwise useless weapons and armor now function as if brand new. By extension it means you have to use fewer kits or spare items to repair your equipment.

Unique weapon repairs draining your caps? Tryhttp://newvegasnexus.com/downloads/file.php?id=34838

I agree. Getting the vendor to repair all those weapons and armor gets costly really quickly. To repair all my stuff, before I got Jury Rigging, it would have cost me upwards past 20000 caps.Sure, I can get that easy playing Caravan, but it's just easier to get the perk. And, as someone else mentioned, it's a much easier way to make caps with all the weapons you find out there.

I took it up to 90 for Jury Rigger and have no regrets doing so. Like someone mentioned earlier, it's a cap gold mine.

This can get very expensive if you have done any modding or have the rare weapons.

its really REALLY helpful. There are a good number of quest that want you to repair stuff. If you have enough repair you can just instantly complete it. Also Jury rigged is AMAZING and really helpful.

Jury rigging is very handy, also, there's a TON of problems in the Mojave wasteland that can be solved using your repair skill.