OK. First off, this has been discussed and rejected before, but I think it is something that really needs to be re-evaluated.
Paragon of Spirits and Focused Paragon of Spirits should be given an endurance regeneration component for a number of reasons. In no particular order of importance :
1) Group/Raid desirability - Underfoot mobs are not nice. Huge damage amounts from melee and spells (several AEs), very high rate of summoning mobs, cramped environments that lead to strange pathing and adds, etc. increase the death rate of PCs. Being able to reduce the rez recovery time in the field for hybrids/melee classes would give us something a lot closer to unique to offer in groups/raids. An endurance component to PoS for raiding is something that's almost necessary now. Raid mobs can burn through tanks very quickly and a slow pickup will leave a number of non tanks dead very quickly. Endurance for Paragon/FPoS would give raids a chance to recover, by allowing us to jumpstart a tanks endurance enough that they can jump back into the fight and be able to disc a bit. From an inside the game perspective, being able to replenish endurance is an ability that would be highly sought after via research and experimentation, with even minimal success being of use.
2) For us -- Endurance replenishment for beastlords has become much more vital. Our melee disc attack burns through endurance noticeably now. Protective Spirit is used much more often. Also, the focus effect on the chest armor increase endurance use even more with empathic fury being able to refresh quicker. Further increases in endurance use are likely to be seen in the future, since we are in need of improved or more defensive disciplines to increase our survival rate. 12 seconds is not really long enough these days, given that it can take a tank longer than that to (re) the undivided attention of a foe, given our occasional damage spikes. After death and a rez, endurance is the killer for getting back into action in a decent interval. If you aren't outside where you can sit on a horse, resummoning and rebuffing is not something that can be done while regaining endurance. This can often lengthen recovery time to a point that annoys groupmates, since the monk bard necro SK shm ber rng ench etc. were all able to survive since you were the only one left stuck in combat with the adds respawns or bad pull. Going through this 10 minute or more song and dance routine for several times in a row can waste far too much time. Not taking the time will often lead to even more deaths . Add the Raid OOc timer in and it gets worse, especially if tossing a buff resets the OOC timer as it sometimes does.
3) It just makes sense. - Not including Endurance regen in paragon is strange IMO. It's akin to being able to put in stiches and put a cast on someone in the ER, but not be able to provide them with oxygen if its needed.
4) Enjoyment - Reducing the recovery time from a solo/group/raid wipe will let people actually play more, rather than sitting around waiting. There is already ample amounts of hurry up and wait time in game, shaving some off with an endurance component for paragon isn't going to destroy the game. If a limit needs to be put on it, cap paragon's endurance regen effects at 33% or 50% of the targets max endurance. This will allow for quicker recovery from deaths etc., without providing an endless well of endurance to fuel constant discing.
If we can present a strong enough case it might even happen. Who knows? Maybe the horse will sing.