Well, I've had feed jams (20 years in the military an all), but never a catastrophic failure on any weapon, personal or professional. I've ever only had to replace firing pins and springs with years (and by that, I mean many years) usage of the same firearm.
On a side not, I personally would never recommend WD40 as a long term lube. It is perfectly fine for short term use, and it is fantastic for mag spring spray (keeps them slicker than owl $H!+). The issue is heat. It was never meant to function under extreme temperatures. I've found that CLP works perfectly and have never had an issue, even with smoking hot barrel, rapid fire, long days on the range usage.
Having said that, I like degradation, I would just like it better implemented. Maintenance and gun parts could easily fit into FO, right along with reloading ammo and crafting makeshift weapon mods. Probably won't happen, all but the last part. I think small weapon part drops (springs, pins -- even RL modifications like vertical grips, extended mags, and holo sights) along with gun oil drops would have been interesting...right along side the current weapon mod crafting system. Suppose you can't have everything.
There was a cool mod in FO3 called Gun Oil, that would allow it to "repair" without always having to use a like item. I always sort of looked at it as a maintenance system. That was kind of neat. Not perfect, certainly simple, but interesting.