Suggestion for changing Critical Strike Chance

As we all know, Crits are one of the few remaining RNG variables that are in the game. Critical strikes are a way of amplifying AD and it is an interesting addition to any game. A lot of people want this changed because things that are luck-based should not be in a competitive game, and rightfully so.

I know this proposal has been suggested before so don't credit me for it.

What if critical strike chance was changed into BONUS AD? ex. 20% crit chance -> 20% bonus AD; 35% crit chance -> 35% bonus AD. The bonuses are additive.

I know 20% bonus AD sounds very high right off the bat because AP has Rabadon's Deathcap. But remember, AD has a crit chance variable which does 200% more damage on such critical hits.

For example, Statikk Shiv currently grants 20% crit.

If you have 100 bonus AD, Statikk Shiv has a 20% chance to turn that 100 AD into 200 AD. In other words, you will be able to deal at least one critical strike per five autoattacks on average.

100 (x4) + 200 (crit attack) = 600 damage ON AVERAGE

Obviously the problem here lies in the "chance" variable as one's damage total within those autoattacks can range from just 500 damage (no crits) to 1,000 damage (all crits) which is an incredible difference.

With the bonus AD suggestion, the 100 bonus AD turns into 120 AD permanently.

Essentially, this change equates to the same amount of damage as the example above but it removes the RNG element to make for a more fair matchup.

120 x (5 autoattacks) = 600 damage guaranteed

For crits, the bonus damage is certainly not guaranteed as it is based on RNG. The five auto attacks with 20% crit should, on average, net you 600 damage in total. With the bonus AD, you will be dealing 600 damage no matter the circumstances and this completely eliminates the finger-crossing element that is RNG.

Thoughts?