weapon skill was changed for a few reasons. First, it was "too good" point-for-point. However, we also made some slight improvements to +weapon skill to offset the nerf in order to maintain its use as the "best" stat you can get against a target 3 levels or higher than you, but not by as wide of a margin. In addition, we didn't want +weapon skill to affect glancing blows because glancing blows (along with crushing blows) are our sacrosanct protection against players fighting mobs they're simply not supposed to be fighting.
Seems like this will cause a major DPS drop for rogues and warrior who are serious enough to stack weapon skill for melee DPS.
Although Kalgan still holds that weapon skill will perform well against 63s, anyone who has experimented with it before knows how amazing an increase even +5 weapon skill is, so this seems like a big deal.