Hmm. INT also handles investigation, which I think is used in exploration, not only perception. Otherwise it is used a bit more in conversations.. All the knowledge skills governed by INT should also be important for identifying magic loot and give info about enemies. But that's not correctly implemented in the game so far. But you're right that INT lost a lot of its importance in the transition to 5e. It sadly even lost its disadvantage being low affecting your ability to speak. Now everyone can speak, read and write fluently by "virtue of its race".
