i dont know how SE has their particle system and effects setup in ffxiv. in some games, spells or projectiles are actually objects that can be triggered if it hits something. i dont think it works that way in ffxiv. if you cast a spell, its only a particle effect on the mob so if something was to be in the way, the object isn't going to block it, the spell would still hit the mob.

i really like the idea of giving spells a lot more modifiers other than dmg. being able to use spells defensively like a wall of ice or a wall of stone to block projectile can add a whole another dimension to NM/Boss fights. right now, the only defensive thing you can do is move out of range of the mobs spell. i think if they stay away from that mechanic, stationary spell casting wont be that big of a deal. instead of running out of range, we can cast a spell that can block projectiles or effect LoS of mobs.