Why Critical Hits are "Unbalanced"

I don't play League nearly as much as I used to, and I have narrowed this down to just a few reasons. The primary reason is that, to me at least, Critical Hits are the single most unbalanced factor in League of Legends. They do not unbalance the game because of the multiplicative boost to the ADC. That damage is acceptable, and the game is designed around it. What is intolerable to me about them is the chance factor. League of Legends presents itself as a sport, but imagine say, a game of basketball, where every time someone scored, the referee flipped a coin, if it was heads, they get double points. The NBA would certainly not keep this around, as it negates player skill in favor of luck, and I cant see why League does the same with Crits.

Now, you might ask, what will happen to all the poor ADC's if Criticals go away? They won't be viable if they lose that damage! However, they don't have to lose any damage, Instead, I propose that Critical Hit Chance be turned into a stat I like to call Precision. Precision would increase basic attack damage (NOT attack damage) by a percentage equal to your precision score, so buying a Phantom Dancer would increase the damage of all of your basic attacks by 30%, instead of increasing the damage of 30% of your basic attacks by 100%. This is also more representative of actual combat, as a critical hit represents hitting a more vital area, which, as any experienced fighter can tell you, is not luck based if you have some training.

But what about Infinity edge? How would that work under this new system? Simple, it increases your Precision by 50% Crit damage runes would follow the same logic, increasing your Precision by x%, and stacking in the same manner as they already do.

Riot, You removed dodge because it was unpredictable and could unbalance the game with a lucky streak, Critical Hit Chance does the same thing, Please let it go the same way.