If Square-Enix directly asked you for suggestions...

[AlexionSkylark]

• Make boss rotation speed adjust automatically in real time to the average DPS taken, updated each second, essentially making it impossible to skip mechanics with high DPS (this would actually cause too much DPS to make the fight HARDER, with mechanics coming sooner and more frequently).
  
• Revert the change to Cleric Stance and healer classes damage (change it back to scaling from INT), still making cleric stance a role skill. But make it work like nocturnal/diurnal sects, meaning you can only change stances outside of battle.
  
• Enhance the damage penalty on tank stances (Shield Oath, Defiance, Grit) to 70% from 20%, enhancing aggro generation accordingly. Also introduce a 30% damage taken penalty on DPS stances (Deliverance / Sword Oath / Darkside). Make it so Survival CDs can't be used while on damage stances.
  
• Nerf how VIT scale HP by about 10~15% of the current factor, effectively lowering everyone's Max HP across all levels. Also buff damage scaling at the root calculation for all enemies in the entire game by about 10%.

Those would be things I'd LOVE to see changed in the game right now.