I say remove them. One less roll which does not really contribute to the game. Just fold it into an attack roll:
MISS CHANCES
Several spells and situations call for rolling of a miss chance, such as darkness, blindness, fog, etc. Reducing the number of die rolls, Miss Chance is no longer used. It is instead applied as a penalty to attack rolls. The penalty is equal to -1 per 5% of miss chance. Feats reducing the Miss Chance reduce the penalty accordingly.
(ARCANE) SPELL FAILURE
If you want to cast a spell with somatic components and are wearing armor or carrying a shield, arcane spell failure chance is ignored. Instead, you are treated as if you were of a lower caster level. Your caster level decreases by -1 per 10% of arcane spell failure chance.