Player choice
I wonder does riot realize all this did was not only reduce player choice, but create a situation in which characters who needed certain stats being incapable of receiving them. Not to mention that some of the masteries like stormraider stabilized some champs. They basically had a safety net in the original rune system that allowed players to alter stats slightly to their preference, and this new system is trash in comparison. They should have went with a mastery rework and left it at that.