It's not like they've reduced any of the stats on dungeon gear. The materia slots are strictly a bonus. You know what else are bonus stats that you can get through the crafting system? Food and stat potions. Next you're going to be saying its unfair to be a/pay a culinarian or alchemist to have access to the stat bonuses you gain from food and the extra cooldown from stat potions. You're no more required or more deserving of having those materia slots filled as you are to have a food buff or stat potions.