Yeah the people who didn't like it didn't like working with negative numbers. I find negative numbers pretty intuitive you get 'lower is better'. And I'm not a math geek but it's not any different that what you use in the supermarket. The advantage of the Thac0 system is that the bounds were right there -- you could never have a raw AC worse than 10 and the gods themselves cannot do better than -10. So from +10 to -10 with zero as the midpoint.
As soon as I heard that the system would be changed for 3rd edition I thought -- sure you can say it makes no difference if you go up rather than down people are going to push that number to absurd heights. And I think that's what happened.
