Agreed.
If you know nothing about guns, you sure as hell aren't going to shoot well. A person that never fired a gun in their life isn't just going to be able to pick up a sniper rifle and snipe people in the head from a great distance. Hell they would be lucky to shoot a person a few yards a way. Sure they could be lucky but not lucky enough to do it over and over again.
Imo fallout has already implemented a system for low weapon skill pretty well in FO3 and FO:NV. It's more plausible in the sense that you cans till use those weapons, but not having the requisite level of skill makes them pretty rubbish for you in terms of accuracy and IIRC condition deterioration. With melee weapons, it obviously wouldn't really be an issue as somebody unskilled but carrying a bat will still have a very good chance of wasting someone with no bat.
As far as lockpicking goes, I like the minigame, but it needs to be a lot harder when your skill level is too low, as in even testing the tension of the lock would break your pick instantly if its in the wrong place. I would like a compromise between Skyrim and Fallout 3/nV's system; where you can attempt locks a certain amount above your skill level, but over that limit locks become unattemptable. So in Skyrim for example you could attempt up to adept locks if your skill level was novice, but not above that, and any lock above your skill level would be disproportionately harder to open. Also, picks should be less obtainable.
However, I would also like the ability to destroy the lock with force, with a high chance of damaging the contents.