Over the course of the game, HP pools have constantly become bigger and bigger.
2 years ago with the launch of Murkmire we saw a big increase in HP in PvP due to changes to racials and overall changes.
Back then the average HP in Cp pvp was around 23-25k very rarely would you meet someone who had 28k or more unless they played actual tank builds.
But in the last 2 years average HP went up to 32k on Pc EU no matter which build you're facing.
Seeing builds with less than 28k HP these days is very rare and most people already tend to run more like 35-38k especially when playing stamden or stamnecro.
Those high HP pools severely hurt PvP and it's flow, overall damage went up over the past 2 years due to set creep and overall balance changes.
However for many classes the damage windows have been drastically increased by numerous (very unpleasant) changes like the removal of almost every single offensive stun.
Dizzying swing? Limited to 1 CC every 22 seconds
Master destro? Reduced to only flame clench which knocks people out of range for meele skills
Off balance stun? Reduced to 1 CC every 22 seconds
This results in many classes having to waste a full gcd to stun the enemy without touching their health bars (fear, fear totem, turn undead, mesmerize, ...) which in conjunction with buffed heals, not so much the case anymore but still relevant, makes things even worse.
By the time you can hit a damage skill on your target it will have healed up to what would have been full health some years ago.
This has also made skills with a traveltime a lot worse, when you need to get your damage off as fast as possible having skills like strife or frags and multiple others, which take 50% or even twice as long to hit a target compared to others, becomes a big disadvantage.
Previously people where much closer to a burstable Hp range with 30k they're very far away from that meaning you could miss a few skills because the target would still be much closer to death than they are nowadays after avoiding a skill and healing back to full.
To make matters worse the casttime on many ultimates increases the timespan further, giving the target even more time to heal or be healed by someone else.
A good example for this is 2 ball groups fighting each other, unless a target dies in one go from 100-0 it won't ever die as there are so many healing instances that they'll be back to 35k HP in no time which is too high for regular damage to kill the target.
A high HP meta also influences classes differently.
Specs like magsorc or magnecro (trash spec) who rely on only having burst every 3 seconds with almost no relevant damage in between struggle a lot in a meta with people having HP pools way beyond what your burst damage is.
This forces magsorcs to often wait until they charge up 300-500 ultimate for overload and than spam it on one target till it finally dies, the original combat flow has heavily changed.
Those changes to combat have also influenced the way which people build, first of all everyone makes sure to reach +30k Hp which isn't really an issue with tri glyphs, sugarskulls, minor toughness on warden etc.
Then many people rejoice to using proc sets over stat boosting sets as those procs offer more damage in a short period of time compared to more damage on every skill but a lot less bursty when running stat sets.
Now one could think that this increase in HP helped closing the gap between good and bad players and helped making the game more fun for worse players because they don't die in 3 seconds, but that's wrong bad players are now far less likely to ever kill a better player unless they heavily outnumber them because earlier they were closer to death but more importantly the good player was also a lot closer to death too and didn't have the huge room for error people have nowadays to stay alive.
And that is how we found ourselves in a meta where procs are everywhere, people are more inclined to stack in zergs thus creating more lag as fights take longer and people stack up in only a few spots on the map.
Build diversity has also taken a huge hit as build have been heavily shifted towards procs and with the introduction of malacath have seen a huge damage buff across the board with no drawback.
Those issues should be tackled by tweaking the following things:
HP bonuses being 10% higher than stamina and magicka bonuses
Minor toughness becoming better the more Hp you stack
HP scaling heals being reworked to only scale well at very high HP pools
Tristat food and glyphs being much more stat dense than other competitors.
Heavy armor offering loads of extra HP
Battle spirit giving 5k extra HP
A sweet spot for average Hp would be somewhere around 25k with 29k being the upper border and everything above requiring heavy investment.
Making regen food like camoran throne or witchmother viable again as they fall way behind compared to tristat food like sugarskulls.