The game is entirely tuned around expecting nobody to have VIT except in edge cases where you're trying to do certain really dangerous content with underlevelled gear (And I mean super high end). The stuff that is going to oneshot you in this game, generally, isn't something that a few extra stat points in VIT will enable you to survive - it's stuff that's not meant to hit you (or at least only your tanks).

Feel free to pump all stat points into INT. If you plan to be swapping regularly between SCH and SMN as you level further (because ACN allows that), you can get away with 15 in each; 15 points is honestly not that severe a difference until we're talking super endgame at which point you'll be able to make the decision to focus/switch much, much easier.