Title : I know what some of you are thinking. We can mod it in. Yes we can, but I think this game could benefit from a vanilla style inventory expansion system. One that promotes not only experiencing the game, but also giving players motivation to do more content.
Maybe after doing 1 mission for Hildir she sells one that expands your inventory rows by 1 entire row for 750g.
Perhaps another is something you need to craft after you beat Yagluth or Moder and use their crafting stations.