Guild Wars 2 Developer Blog

Guild Wars 2 systems designer Isaiah Cartwright has penned a new pre-PAX East developer blog update on ArenaNet's iterative design process, using attribute redesign as an example.
When coming up with this system, there was an ongoing debate over combining strength, agility, and intelligence. We decided to keep them separate since we found it made an interesting decision about focusing on ranged or melee attack power.

This attribute system worked pretty well, but the decision that we were originally excited by proved to have major downsides. You could make a warrior carrying a sword and bow in your two weapon slots, which was not uncommon for players to want. Unfortunately, if you split your attribute points between strength and agility, you were less effective overall than someone who carried two melee or ranged weapons and specialized appropriately. Our first solution to this problem was to add traits into the system that forced your ranged attacks to use your melee attribute and vice versa. This added some neat traits to our system, but it didn't solve the underlying problem that someone could very easily roll a bad character. The other problem we found was that this system limited experimentation and discovery. We want players to have fun trying out new weapons. If a player with a warrior locates a rifle, we want them to enjoy testing out its different skills and possibly working it into their active weapon set. We discovered this experimentation isn't nearly as much fun if you didn't spend your attributes properly to take advantage of this new weapon. Finally, we determined that willpower was fairly unexciting as attributes go, as many people avoided putting points into it. Recently, we've changed the attribute system to be simpler, and it solves many of the above issues.