Intelligence is still pretty handy since it affects the XP gain rate. That said, I've gone and made a Strength/Endurance melee guy with barely any Int, Per, Cha, Agi or Luck. Surprisingly, I'm having a pretty fun time with it. Finished my first session with the game just then and ended up with a fully modded sick as fuck chained aluminum baseball bat and a set of studded leather armour. I've only done one or two quests, got most of my XP by just exploring and killing shit. 10/10 game so far (though loading screens on PS4 are shit).