I think that main problem is this heto talent are not feeling cool enough. Like look at diabolist - what can be more warlocky then summoning freaking pitlord?
Maybe Collosus warrior look okeish, i think? If that strike will have coll visuals and effect on gameplay.
But druid trees are just empowering your 1 spell? And thats all?
Give something to feel satisfying to use.
Give warrior call of ancients from diablo to summor pair of champions.
Give mage to rain fire from the sky. Big one, not fire shower.
Give shamans to feel UNLIMITED POWER. As palpatine.
If you empower treants with CotG spec - they should be massive, they should do a yon of damage.
If you elune chosen - do HUGE lazor from sky.
You now, HERO stuff, not boring plebs stuff.
To balance things out - best way, in my opinion, is to replace each hero spec accent to burst button. Like instead boring reincarnation if druid - give each of hero talent new powerfull upgrade.
Instead of wings of paladin - let them throw hugeass hammer on the ground that deal a ton of damage.
Instead of dark arrow boring dot - let it summon pair of undead dogs that deal shadow damage.
Instead of combustion - frostfire mage start raining frostfire meteors.
And so on and on.