Hussar
Legend
In 1E you coulf hit (almost) anything with non-magical items if they were made of the right stuff. E.g. a cold iron weapon could hit any demon and a silver one could hit any devil. Many undead could be hit by silver also (but not all). Even the toughest demons and devils (excluding lords, princes, archdevils, etc) had an AC of about 25 (in 3E terms). A 9th level fighter with a decent STR (let's say 17) and double weapon specialization would hit that AC on a roll of 13 or higher, and all of his attacks hit on the same odds as the first, so a F9 without a magic weapon wasn't useless against demons, devils, or undead by any means.
Really? Virtually any undead over 4 HD could only be hit by magical weapons, not silver - it started with Wights and carried on. Gargoyles also had no particular weaknesses. Demons and devils, sure, but, that presumed that you KNEW that you would be facing one or the other, or you carried a golf bag full of different weapons.
I think that if you actually looked at the weapon immunities in AD&D, you'd find that most creatures didn't have specific weaknesses.
Now, it's true that your PC's were MUCH stronger vs creatures in AD&D than in 3e and 4e. As you said, a Fighter 9 with a pretty minimal strength is still hitting virtually every round vs the strongest of AC's. Again, this isn't true in 3e or 4e. In 3e or 4e, a fighter with a minimal Str and no magical enhancements is probably hitting mid range AC's regularly, but the high AC's are right out of reach.
Bill91 - the problem I found with the item creation feats in my game (beyond wands and scrolls) is the caster classes started getting VERY testy when the non-casters kept bugging them to make magic items at cost. It's not like the fighter was losing Xp when the wizzie made a magic sword, nor did the fighter have to take any down time. Nor did the fighter have to burn feats in order to make those magic items in the first place.
While the groups I played with made liberal use of scrolls, potions and miscelaneous magic items and wands, I rarely, if ever, saw weapons or armor get created.