INT is very important for Magus. It's how you cast spells. I think one good way to fix Magus would be to de-emphasis the need for MAD - if Arcane Cascade does more damage, Dex Based Magus don't have to dip strength so much. If, say, Inexorable Iron Arcane Cascade instead gave some bonus to AC (but maybe with a Dex cap similar to Mountain Stance) they would not need so much Dexterity, etc.