Looking at the ICME Advanced Magic system, it seems to have become a form of Vancian/spell slot/limited resource magic system. You have a set of Stun Points that you spend to cast spells. Once you spend all your SP you can no longer cast spells. Unlike Vigilante City you can’t recover these Stun Points with a recovery roll. You can recover SP with a long rest in safety (or potions).
Personally, I dislike Vancian magic. One of the appeals of ICRPG to me is the “roll to cast” system. I also like the ICRPG:Magic system because there’s a way to recover HP (Recovery roll).
I know I can just use the “roll to cast” in ICME or house rule the SP recovery from Vigilante City for Advanced Magic (or even use the ICRPG:Magic system), but I’m wondering what was the reason for this change. There’s already limitations/danger for using Magic in ICRPG/ICME: Spell Burn, Mercurial Mishaps.