Please, don't just blindly look at raw stats.

Currently on the PBE, there are BIG changes regarding ADC itemization, yet people fail to realize how strong they are. The main changes are a mini rework of IE, removing its original critical strike chance and damage, and instead doubles your current crit chance, and converts some of your critical strikes into true damage. Doing some math, you can see that the overall damage on crits is nerfed. The item also costs 300 more gold.

Zeal upgrades items also cost 200 more gold now.

If you wanna talk about how the raw stats and damage is not changed by a lot, therefore making this nerf useless, you need to factor in the cost of these items. The 3 item powerspike now costs 700 more gold. Do you realize how much that is? It almost nullifies the entirety of a solo first tower gold. Imagine taking first tower, and getting 0 gold out of it. Imagine having to pick up 5 minion waves for nothing. Or clearing your entire side of the jungle. Or 2 kills and 1 assist.

The changes are big, not because of the direct damage nerfs, but because of the ramp-up time required to get to that damage. If that powerspike is delayed by 3 minutes (assuming the 5-6 minion waves), that's HUGE. That's 3 extra minutes where the ADC player is not as strong as they desire to be, and therefore less effective and more prone to getting killed by an enemy assassin, creating a chain of events that can turn the games to different states than currently.