Yes, macros are much more versatile. But I don't believe that all spells need a macro. Fireball for instance. I don't need to put the modifiers in there that cancel it if the mob is dead or friendly or doesn't exist... wow already wont cast a fireball at a friendly target, or a dead one, or one that doesn't exist. (/cast [target=god] fireball. WoW:"Error, unit does not exist")

Macros are good for /castsequences though... so you'll never get rid of macros all together. What I do like about the mod is I can switch out the spell that goes on that button on the fly without having to edit a macro.