My join date is from some of the first betas but I thought the game sucked ass then and only started playing it again about 4 months ago.If you've been here a while you'll know Stam has been pretty OP for a while - and in many circumstances still are so any nerfs were just to bring a bit of balance .
Stam ultimately fell out because shields are more valuable than mitigation. Stam can mitigate a lot more damage over time and can DPS whilst self-healing with superb mitigation - but AOE DOT damage isn't a real threat in any trial making the unique defensive toolkit of stam pretty pointless. AOE burst is the real threat in trials towards DPS, and shields are significantly better suited for dealing with that than the mitigation and hots stam has.
Now, the resource change will secure some stam bubbas spots in trials as stam is nowhere close to as reliant on warlord as mag is magician and where they have the naturally higher ST/DPS discounting raid buffs (to include sustain buffs), I expect most raid groups to incorporate stam back into the raid meta due to their sustained DPS. Current mag builds will be shoehorned into an AOE burst build due to the the huge increase in costs they will take come Morrowind. Mag toons will have to sacrifice far too much to be able to sustain DPS - enough to the point it's flat out better to just bring stam to the fight.
The disparity in surviability still must be addressed though.
If you've been here a while you'll know Stam has been pretty OP for a while - and in many circumstances still are so any nerfs were just to bring a bit of balance .