From what I understand its something like 10% or less of summoners who fall into the gold or higher category to qualify for the skin. GG Riot, make it for just about nobody...
It's a reward for people who actively seek to get better. It would be unfair to not reward the people who put tons of time and effort into this game to get better.
Besides, everyone gets a reward. More effort, more reward. Seems pretty logical to me.