I run a B/X game for a few guys, most of whom have only played 3E before. It leads to a lot of talk about the change in power level between basic and 3E. One of the things that came up was the somewhat lower attribute modifiers and bonuses.
"Oh man!" I exclaimed. "I bet you guys don't know about percentile strength!"
So, I pulled up the 1E PHB and I was blown away myself to see just how much more powerful 18/00 was compared to plain old 18. A cleric with 18 strength gets +2 damage, while a fighter with 18/00 gets +6. Wow! I remember loving the extra roll being a possibility as a player, and hating the possibility for such a massive bonus as a DM. I don't think it ever came up in play, either way.
Where did this system come from? Was it just invented for AD&D 1E, or was it prefigured in a Dragon article, or what?
UPDATE: Given that aramis pointed out its origin in OD&D's Greyhawk, I doubt we'll find anything on the motivation for it, but if anyone finds that, I would still be quite interested. (Speculation like "Gary wanted to give more damage bonus to strong character" can be omitted, unless we find evidence.)