I don't know about the new numbers, but with the old gold efficiency buying AD was flat-out worse for auto-attackers than buying critical hit chance after ~144 AD. After one real AD item, it was better to get attack speed and crit. That's why the ADC build has been Rush IE into Phantom Dancer for so long. The only reason to buy more AD after that was because it happened to be attached to the stats they really wanted - lifesteal and armour penetration.
If there was a lifesteal + crit chance item, ADCs would grab that instead of The Bloodthirster. If there was a crit chance + percent armour penetration item, ADCs would grab that instead of Last Whisper. Regardless of the (quite low) odds of a bad string of non-crits, your expected damage output increases more by buying critical hit chance.
Hearing people whine about "the probability that you will crit" is like the reverse of people that buy a lottery ticket every week. "I might not crit!" True, but you probably will and the difference in damage more than makes up for the risk.