"For now the game mostly penalize you for not playing it in multiplayer."
Given how the four available companions fill all the rolls needed... (except maybe a dedicated fire and earth mage)
Not seeing the penalty.
If you had bothered to read the paragraph just above, you might have understood that I took the main character Ifan and builded him not as the intended role, a strenght based warrior. Only to realise that I could only recruit the predefined origin characters with their already built in stats/points/skill/talent.
If I had played with 4 players they could all have changed the intended roles of each origin characters, hence playing with 4 players is more advantageous.