I don't really understand why they thought that critical's time had come again?
It's the most radical change in the whole of Pathfinder 2 and frankly also the worst thing to crawl back off of the slab of bad game design idea's imho.
Spikes in damage may be exciting to some but once people have lost enough characters to bad rolls rather than bad tactics I think they will regret its inclusion.
They threw in mandatory Hero Points as a band aid to cover some of the spikes but that just means they lost all the drama they built by letting everyone die once per session for free before they really need to worry.
Do they really want the bad old days where people would roll up a batch of chars so that they could slot poor sob number two in after number one had died?
It doesn't lead to a lot of character development / player investment.