My preference still lies with the endurance/health system from POE1 as well and I can't see the current one in the Beta doing things better in any way. If anything it does things worse than POE1 with the often mentioned
a. fixed number of injuries and
b. the missing strategic component of balancing and maintaining short-term endurance vs. mid-term/long-term health.
I also wouldn't know (yet) how to bring back b. without completely replacing the current one with the endurance/health system from POE1, which of course would be the most preferable solution, but for a. it may be merely a matter of very minor GUI redesign with a small change to how one of the primary attributes affects the max count of injuries.
As already suggested by @eisenschwein and others it would only make sense to let Constitution control how many injuries a character can receive before dying.
Increase the max injury count by 1 every 2nd point in Constitution.
CON 1 -> max injury limit: 1
CON 3 -> max injury limit: 2 (CON 3 was the lowest you could go in POE1, I believe it's still the same in the Beta character creation?)
CON 5 -> max injury limit: 3
Con 11 -> max injury limit: 6
CON 19 -> max injury limit: 10
This way the player character's chosen class (and accordingly distributed attribute points) as well as the NPCs/companions' classes would also be properly reflected in their different max injury limits. There would be not only distinction in how the different classes or builds participate in combat (melee, ranged, magic) there would also be distinction in how much they can take and absorb before reaching the limit and dying the final death.
Should Maneha, a Barbarian (CON 19 in my last playthrough of POE1), not be able to soak up considerably more damage or accumulate significantly more injuries than Aloth, a Wizard (still base CON 10 in my last playthrough of POE1)?
Two concepts for the corresponding redesign of the injury meter necessary to support the proposed revision:
Yep, had something in mind along those lines.
Simple (to implement) yet making quite a difference in regards to what you'd expect from a character with high constitution vs. a character with low constitution in terms of perseverance or pain tolerance, if you will. It does indeed make little sense that an archetypical barbarian and an archetypical wizard should falter or fall from sustaining the exact same, rather low amount of wounds or injuries, unless they're built specifically around and with that in mind.
UI-wise definitely an improvement over the "traffic light" too.
Nice touch with the skull as well.