I don't understand the thought process behind the Precision mastery

Instead of forcing people to pick between 5 mastery points in magic pen or 5 points in armor pen (like in the ferocity page), the mastery is combined into one that provides both magic pen and armor pen. This is bad design because only some champions (hybrid champions) benefit from both magic and physical penetration, making the mastery half as affective for strictly magic or physical damaging champions.

Another point, the ferocity page offers both % mage pen and armor pen, but only allows 5 points in the one line. Why not permit 5 points in both masteries for offensive hybrid builds, at the expense of other masteries. I know this was an option in the s5 masteries. Why remove this diversity?