Limit benefits of crit
I am of the mind that Critical strikes should have a maximum amount of damage they can do. There is a damage threshold that exists that strays into "burst" damage and crits should NEVER get anywhere near that. At the moment we have classes able to crit for 1000 damage which is retarded.
The so-called "burst classes" can hit for 1-2k damage only after they've used all, if not most, of their abilities. The classes that I feel are burst classes, are Mages, and Assassins. They specialize in dealing a ton of damage in a very short span of time by themselves. When you have a ADC capable of critting for 600-1000 damage per hit, that is way too much. They don't have to use any abilities for this and can do it repeatedly over a few seconds easily topping Mages and Assassins in damage, effectively making ADCs the true burst classes. ADCs have more or less rendered Mages and Assassins obsolete because their crit outputs are ludicrously high.
I think crit damage should be capped to maximum of 500 damage per hit and no higher. You say ADCs will not be able to kill something? Build more attack speed then. Attack speed is more expensive than straight damage thus by limiting the effect of crits it will also help curb the insane snowball rates of ADCs by making them reliant on things like attack speed to pull ahead.
ADCs have no business doing 600+ damage per hit since all they have to do is right click. the only classes that have any buisiness hitting that hard per hit are Mages and Assassins, both who have cooldowns and mana costs to contend with.