I just never needed it. Magicka regen was high, even in combat, and I rarely needed to recast the cloaks, but when I did there were enough layers of protection that reducing the cost wasn't necessary. The main situation I used the cloak in was against undead who had detected me and were making for melee combat. It granted passive damage when in Mist Form(during which magicka could continue to safely regen), so once cast, there wasn't any other spell I used after except Bound Bow. Other than that, it was the cloak fortified with potions, and my physical bow.
So it's a situational spell, but gathering artifacts and getting words of power would have been incredibly tedious without it.
I just never needed it. Magicka regen was high, even in combat, and I rarely needed to recast the cloaks, but when I did there were enough layers of protection that reducing the cost wasn't necessary. The main situation I used the cloak in was against undead who had detected me and were making for melee combat. It granted passive damage when in Mist Form(during which magicka could continue to safely regen), so once cast, there wasn't any other spell I used after except Bound Bow. Other than that, it was the cloak fortified with potions, and my physical bow.
So it's a situational spell, but gathering artifacts and getting words of power would have been incredibly tedious without it.