Yes, someone can explain. Killars can. Why are you asking us to explain why an individual, who doesn't post here, is doing something contrary?
I have looked at one of the top combat rogue and seems like he is not following to reforging recommendations: Killars @ Alterac Mountains - Game - World of Warcraft
He is not capped in expertise and put almost everything into hit.
I think he is doing this on purpose. Could anybody please explain?
Another strange thing is that he is using [Glyph of Eviscerate] instead of [Glyph of Slice and Dice].