The great thing about decoupling attributes from to hit chance for me, is that it lets us put a bit more role-playing into the game again. If everyone is compelled to have an 18 in their primary, then you get nothing but a run of hyper-strong fighters, super-agile rogues and genius wizards. We had a fighter who was a tough mercenary woman. We didn't want her to be a towering wall of muscle, just tough and a skilled and experienced soldier. I think we compromised with a Strength of 16, but the difference between her and the 18 Strength fighter was noticeable and next time around, it's going to be another 18 Strength'er. The warlock was similar in that the player just wanted someone who was generally smart and capable all around. That one really paid the price.
If you decouple the attributes (partially), then you can get back to realistic ranges of ability. And that variety is good for role-playing.
If you decouple the attributes (partially), then you can get back to realistic ranges of ability. And that variety is good for role-playing.