Honestly, to me the hit detection changes have actually been fairly beneficial and allowed me to do things I couldn't do otherwise, like moving AOEs before they go off so they snapshot better. I also do not have any issues with the Purify reaction time because it is nigh-instant for me, same for Guard - I guarded vs Primal Rend about 0.1s before impact the other day.
I am not discrediting the experience here, but there is clearly a factor they completely ignored when designing these changes - LATENCY.
For context I play at 10ms (10 Ping) as I live in Germany connecting to a german datacenter (Light + Chaos) through a VPN to ensure I get a direct connection with basically no hiccups. I literally do not have "any" issues regarding hitreg and anytime I miss, it's actually my fault.
Inversely, this means that this netcode is working, but is absolutely brutal at latency exceeding 50-70ms. Things like stuns hitting after pressing Guard making Guard go on cooldown, Resilience not protecting against follow-up CC in time, AOEs not landing (particularly position based AOEs like Holy Sheltron bomb, Impalement, Bioblaster, etc.) are MAJORLY affected by latency, as you are actually no longer snapshotting at a single point in time where you know the player is for sure, but you have to track them where they actually "might be".
It will favour you at low latency, it will be basically soft-gambling at high latency. Given North America Datacenter location(s) generally being unable to favour the entire region at once and JP being a relatively small region (geographically), it makes sense they did not consider high latency when designing the netcode changes.
"Technically" how it works is just different from what we are used to and can be learned, but our network infrastructure world wide does not allow for low latency gaming worldwide, let alone regionwide. As long as this is a factor, this will remain a problem, therefore this netcode without adjustments is flawed.