Not sure why they think it's going to be easier to chill/shock late game bosses when there's no way you are going to be hitting a Guardian for 10% of its life in one hit unless you are playing a very specialize build.Dev manifesto #2 on charges + chill/shock:
https://www.pathofexile.com/forum/view-thread/1929712
TL;DR: Charge changes reverted, chill/shock now require dmg dealt equal of 10% of max hp to be max effective.
I guess you can shock a boss for 5% extra damage (which is 1% of maximum efficiency) if you hit them for something that does 1/100th of their life. It's not that bad I guess, maybe if you invest in the point you can actually shock/chill Guardians somewhat reasonably.
Also Power Charges don't give Spell damage anymore? I thought that was a nice change.